Within months of taking office, President Donald Trump is likely to face one or more major international crises, possibly entailing a risk of nuclear escalation. Not since the end of the Cold War has a new chief executive been confronted with as many potential flashpoints involving such a risk of explosive conflict. This proliferation of crises has been brewing for some time, but the situation appears especially ominous now, given Trump’s pledge to bring American military force swiftly to bear on any threats of foreign transgression. With so much at risk, it’s none too soon to go on a permanent escalation watch, monitoring the major global hot spots for any sign of imminent flare-ups, hoping that early warnings (and the outcry that goes with them) might help avert catastrophe.

Looking at the world today, four areas appear to pose an especially high risk of sudden crisis and conflict: North Korea, the South China Sea, the Baltic Sea region, and the Middle East. Each of them has been the past site of recurring clashes, and all are primed to explode early in the Trump presidency.

Why are we seeing so many potential crises now? Is this period really different from earlier presidential transitions?

It’s true that the changeover from one presidential administration to another can be a time of global uncertainty, given America’s pivotal importance in world affairs and the natural inclination of rival powers to test the mettle of the country’s new leader. There are, however, other factors that make this moment particularly worrisome, including the changing nature of the world order, the personalities of its key leaders, and an ominous shift in military doctrine.

Just as the United States is going through a major political transition, so is the planet at large. The sole-superpower system of the post–Cold War era is finally giving way to a multipolar, if not increasingly fragmented, world in which the United States must share the limelight with other major actors, including China, Russia, India, and Iran. Political scientists remind us that transitional periods can often prove disruptive, as “status quo” powers (in this case, the United States) resist challenges to their dominance from “revisionist” states seeking to alter the global power equation. Typically, this can entail proxy wars and other kinds of sparring over contested areas, as has recently been the case in Syria, the Baltic, and the South China Sea.

This is where the personalities of key leaders enter the equation. Though President Obama oversaw constant warfare, he was temperamentally disinclined to respond with force to every overseas crisis and provocation, fearing involvement in yet more foreign wars like Iraq and Afghanistan. His critics, including Donald Trump, complained bitterly that this stance only encouraged foreign adversaries to up their game, convinced that the United Stateshad lost its will to resist provocation. In a Trump administration, as The Donald indicated on the campaign trail last year, America’s adversaries should expect far tougher responses. Asked in September, for instance, about an incident in the Persian Gulf in which Iranian gunboats approached American warships in a threatening manner, he typically told reporters, “When they circle our beautiful destroyers with their little boats and make gestures that…they shouldn’t be allowed to make, they will be shot out of the water.”

Although with Russia, unlike Iran, Trump has promised to improve relations, there’s no escaping the fact that Vladimir Putin’s urge to restore some of his country’s long-lost superpower glory could lead to confrontations with NATO powers that would put the new American president in a distinctly awkward position. Regarding Asia, Trump has often spoken of his intent to punish China for what he considers its predatory trade practices, a stance guaranteed to clash with President Xi Jinping’s goal of restoring his country’s greatness. This should, in turn, generate additional possibilities for confrontation, especially in the contested South China Sea. Both Putin and Xi, moreover, are facing economic difficulties at home and view foreign adventurism as a way of distracting public attention from disappointing domestic performances.

These factors alone would ensure that this was a moment of potential international crisis, but something else gives it a truly dangerous edge: a growing strategic reliance in Russia and elsewhere on the early use of nuclear weapons to overcome deficiencies in “conventional” firepower.

For the United States, with its overwhelming superiority in such firepower, nuclear weapons have lost all conceivable use except as a “deterrent” against a highly unlikely first-strike attack by an enemy power. For Russia, however, lacking the means to compete on equal terms with the West in conventional weaponry, this no longer seems reasonable. So Russian strategists, feeling threatened by the way NATO has moved ever closer to its borders, are now calling for the early use of “tactical” nuclear munitions to overpower stronger enemy forces. Under Russia’s latest military doctrine, major combat units are now to be trained and equipped to employ such weapons at the first sign of impending defeat, either to blackmail enemy countries into submission or annihilate them.

Following this doctrine, Russia has developed the nuclear-capable Iskander ballistic missile (a successor to the infamous “Scud” missile used by Saddam Hussein in attacks on Iran, Israel, and Saudi Arabia) and forward deployed it to Kaliningrad, a small sliver of Russian territory sandwiched between Poland and Lithuania. In response, NATO strategists are discussing ways to more forcefully demonstrate the West’s own capacity to use tactical nuclear arms in Europe, for example by including more nuclear-capable bombers in future NATO exercises. As a result, the “firebreak” between conventional and nuclear warfare—that theoretical barrier to escalation—seems to be narrowing, and you have a situation in which every crisis involving a nuclear state may potentially prove to be a nuclear crisis.

With that in mind, consider the four most dangerous potential flashpoints for the new Trump administration.

North Korea

North Korea’s stepped-up development of nuclear weapons and long-range ballistic missiles may present the Trump administration with its first great international challenge. In recent years, the North Koreans appear to have made substantial progress in producing such missiles and designing small nuclear warheads to fit on them. In 2016, the country conducted two underground nuclear tests (its fourth and fifth since 2006), along with numerous tests of various missile systems. On September 20th, it also tested a powerful rocket engine that some observers believe could be used as the first stage of an intercontinental ballistic missile (ICBM) that might someday be capable of delivering a nuclear warhead to the western United States.

North Korea’s erratic leader, Kim Jong-un, has repeatedly spoken of his determination to acquire nuclear weapons and the ability to use them in attacks on his adversaries, including the United States. Following a series of missile tests last spring, he insisted that his country should continue to bolster its nuclear force “both in quality and quantity,” stressing “the need to get the nuclear warheads deployed for national defense always on standby so as to be fired at any moment.” This could mean, he added, using these weapons “in a preemptive attack.” On January 1st, Kim reiterated his commitment to future preemptive nuclear action, adding that his country would soon test-fire an ICBM.

President Obama responded by imposing increasingly tough economic sanctions and attempting—with only limited success—to persuade China, Pyongyang’s crucial ally, to use its political and economic clout to usher Kim into nuclear disarmament talks. None of this seemed to make the slightest difference, which means President Trump will be faced with an increasingly well-armed North Korea that may be capable of fielding usable ICBMs within the coming years.

How will Trump respond to this peril? Three options seem available to him: somehow persuade China to compel Pyongyang to abandon its nuclear quest; negotiate a disarmament deal directly with Kim, possibly even on a face-to-face basis; or engage in (presumably nonnuclear) preemptive strikes aimed at destroying the North’s nuclear and missile-production capabilities.

Imposing yet more sanctions and talking with China would look suspiciously like the Obama approach, while obtaining China’s cooperation would undoubtedly mean compromising on trade or the South China Sea (either of which would undoubtedly involve humiliating concessions for a man like Trump). Even were he to recruit Chinese President Xi as a helpmate, it’s unclear that Pyongyang would be deterred. As for direct talks with Kim, Trump, unlike every previous president, has already indicated that he’s willing. “I would have no problem speaking to him,” he told Reuters last May. But what exactly would he offer the North in return for its nuclear arsenal? The withdrawal of US forces from South Korea? Any such solution would leave the president looking like a patsy (inconceivable for someone whose key slogan has been “Make America Great Again”).

That leaves a preemptive strike. Trump appears to have implicitly countenanced that option, too, in a recent tweet. (“North Korea just stated that it is in the final stages of developing a nuclear weapon capable of reaching parts of the U.S. It won’t happen!”) In other words, he is open to the military option, rejected in the past because of the high risk of triggering an unpredictable response from the North, including a cataclysmic invasion of South Korea (and potential attacks on US troops stationed there). Under the circumstances, the unpredictability not just of Kim Jong-un but also of Donald Trump leaves North Korea in the highest alert category of global crises as the new era begins.

The South China Sea

The next most dangerous flashpoint? The ongoing dispute over control of the South China Sea, an area bounded by China, Vietnam, the Philippines, and the island of Borneo. Citing ancient ties to islands in those waters, China now claims the entire region as part of its national maritime territory. Some of the same islands are, however, also claimed by Brunei, Malaysia, Vietnam, and the Philippines. Although not claiming any territory in the region itself, the United States has a defense treaty with the Philippines, relies on free passage through the area to move its warships from bases in the Pacific to war zones in the Middle East, and of course considers itself the preeminent Pacific power and plans to keep it that way.

In the past, China has clashed with local powers over possession of individual islands, but more recently has sought control over all of them. As part of that process, it has begun to convert low-lying islets and atolls under its control into military bases, equipping them with airstrips and missile defense systems. This has sparked protests from Vietnam and the Philippines, which claim some of those islets, and from the United States, which insists that such Chinese moves infringe on its Navy’s “freedom of navigation” through international waters.

President Obama responded to provocative Chinese moves in the South China Sea by ordering US warships to patrol in close proximity to the islands being militarized. For Trump, this has been far too minimal a response. “China’s toying with us,” he told David Sanger of the New York Times last March. “They are when they’re building in the South China Sea. They should not be doing that but they have no respect for our country and they have no respect for our president.” Asked if he was prepared to use military force in response to the Chinese buildup, he responded, “Maybe.”

The South China Sea may prove to be an early test of Trump’s promise to fight what he views as China’s predatory trade behavior and Beijing’s determination to resist bullying by Washington. Last month, Chinese sailors seized an American underwater surveillance drone near one of their atolls. Many observers interpreted the move as a response to Trump’s decision to take a phone call of congratulations from the president of Taiwan, Tsai Ing-wen, shortly after his election victory. That gesture, unique in recent American presidencies, was viewed in Beijing, which considers Taiwan a renegade province, as an insult to China. Any further moves by Trump to aggravate or punish China on the economic front could result in further provocations in the South China Sea, opening the possibility of a clash with US air and naval forces in the region.

All this is worrisome enough, but the prospects for a clash in the South China Sea increased significantly on January 11th, thanks to comments made by Rex Tillerson, the former CEO of ExxonMobil and presumptive secretary of state, during his confirmation hearing in Washington. Testifying before the Senate Foreign Relations Committee, he said, “We’re going to have to send China a clear signal that, first, the island-building stops and, second, your access to those islands also is not going to be allowed.” Since the Chinese are unlikely to abandon those islands—which they consider part of their sovereign territory—just because Trump and Tillerson order them to do so, the only kind of “signal” that might carry any weight would be military action.

What form would such a confrontation take and where might it lead? At this point, no one can be sure, but once such a conflict began, room for maneuver could prove limited indeed. A US effort to deny China access to the islands could involve anything from a naval blockade to air and missile attacks on the military installations built there to the sinking of Chinese warships. It’s hard to imagine that Beijing would refrain from taking retaliatory steps in response, and as one move tumbled onto the next, the two nuclear-armed countries might suddenly find themselves at the brink of full-scale war. So consider this our second global high alert.

The Baltic Sea Area

If Hillary Clinton had been elected, I would have placed the region adjoining the Baltic Sea at the top of my list of potential flashpoints, as it’s where Vladimir Putin would have been most likely to channel his hostility to her in particular and the West more generally. That’s because NATO forces have moved most deeply into the territory of the former Soviet Union in the Baltic states of Latvia, Estonia, and Lithuania. Those countries are also believed to be especially vulnerable to the kind of “hybrid” warfare—involving covert operations, disinformation campaigns, cyberattacks, and the like—that Russia perfected in Crimea and Ukraine. With Donald Trump promising to improve relations with Moscow, it’s now far less likely that Putin would launch such attacks, though the Russians continue to strengthen their military assets (including their nuclear war-fighting capabilities) in the region, and so the risk of a future clash cannot be ruled out.

The danger there arises from geography, history, and policy. The three Baltic republics only became independent after the breakup of the USSR in 1991; today, they are members of both the European Union and NATO. Two of them, Estonia and Latvia, share borders with Russia proper, while Lithuania and nearby Poland surround the Russian enclave of Kaliningrad. Through their NATO membership, they provide a theoretical bridgehead for a hypothetical Western invasion of Russia. By the same token, the meager forces of the three republics could easily be overwhelmed by superior Russian ones, leaving the rest of NATO to decide whether and in what fashion to confront a Russian assault on member nations.

Following Russia’s intervention in eastern Ukraine, which demonstrated both Moscow’s willingness and ability to engage in hybrid warfare against a neighboring European state, the NATO powers decided to bolster the alliance’s forward presence in the Baltic region. At a summit meeting in Warsaw in June 2016, the alliance agreed to deploy four reinforced multinational battalions in Poland and the three Baltic republics. Russia views this with alarm as a dangerous violation of promises made to Moscow in the wake of the Cold War that no NATO forces would be permanently garrisoned on the territory of the former Soviet Union. NATO has tried to deflect Russian complaints by insisting that, since the four battalions will be rotated in and out of the region, they are somehow not “permanent.” Nevertheless, from Moscow’s perspective, the NATO move represents a serious threat to Russian security and so justifies a comparable buildup of Russian forces in adjacent areas.

Adding to the obvious dangers of such a mutual build-up, NATO and Russian forces have been conducting military “exercises,” often in close proximity to each other. Last summer, for example, NATO oversaw Anaconda 2016 in Poland and Lithuania, the largest such maneuvers in the region since the end of the Cold War. As part of the exercise, NATO forces crossed from Poland to Lithuania, making clear their ability to encircle Kaliningrad, which was bound to cause deep unease in Moscow. Not that the Russians have been passive. During related NATO naval exercises in the Baltic Sea, Russian planes flew within a few feet of an American warship, the USS Donald Cook, nearly provoking a shooting incident that could have triggered a far more dangerous confrontation.

Will Putin ease up on the pressure he’s been exerting on the Baltic states once Trump is in power? Will Trump agree to cancel or downsize the US and NATO deployments there in return for Russian acquiescence on other issues? Such questions will be on the minds of many in Eastern Europe in the coming months. It’s reasonable to predict a period of relative calm as Putin tests Trump’s willingness to forge a new relationship with Moscow, but the underlying stresses will remain as long as the Baltic states stay in NATO and Russia views that as a threat to its security. So chalk the region up as high alert three on a global scale.

The Middle East

The Middle East has long been a major flashpoint. President Obama, for instance, came to office hoping to end US involvement in wars in Iraq and Afghanistan, yet US troops are still fighting in both countries today. The question is: How might this picture change in the months ahead?

Given the convoluted history of the region and its demonstrated capacity for surprise, any predictions should be offered with caution. Trump has promised to intensify the war against ISIS, which will undoubtedly require the deployment of additional American air, sea, and ground forces in the region. As he put it during the election campaign, speaking of the Islamic State, “I would bomb the shit out of them.” So expect accelerated air strikes on ISIS-held locations, leading to more civilian casualties, desperate migrants, and heightened clashes between Shiites and Sunnis. As ISIS loses control of physical territory and returns to guerilla-style warfare, it will surely respond by increasing terrorist attacks on “soft” civilian targets in neighboring Iraq, Jordan, and Turkey, as well as in more distant locations. No one knows how all this will play out, but don’t be surprised if terrorist violence only increases and Washington once again finds itself drawn more deeply into an endless quagmire in the Greater Middle East and northern Africa.

The overriding question, of course, is how Donald Trump will behave toward Iran. He has repeatedly affirmed his opposition to the nuclear deal signed by the United States, the European Union, Russia, and China and insisted that he would either scrap it or renegotiate it, but it’s hard to imagine how that might come to pass. All of the other signatories are satisfied with the deal and seek to do business with Iran, so any new negotiations would have to proceed without those parties. As many US strategists also see merit in the agreement, since it deprives Iran of a nuclear option for at least a decade or more, a decisive shift on the nuclear deal appears unlikely.

On the other hand, Trump could be pressured by his close associates—especially his pick for national security advisor, retired Lieutenant General Michael Flynn, a notoriously outspoken Iranophobe—to counter the Iranians on other fronts. This could take a variety of forms, including stepped-up sanctions, increased aid to Saudi Arabia in its war against the Iranian-backed Houthis in Yemen, or attacks on Iranian proxies in the Middle East. Any of these would no doubt prompt countermoves by Tehran, and from there a cycle of escalation could lead in numerous directions, all dangerous, including military action by the United States, Israel, or Saudi Arabia. So mark this one as flash point four and take a deep breath.

Going on Watch

Starting on January 20th, as Donald Trump takes office, the clock will already be ticking in each of these flashpoint regions. No one knows which will be the first to erupt, or what will happen when it does, but don’t count on our escaping at least one, and possibly more, major international crises in the not-too-distant future.

Given the stakes involved, it’s essential to keep a close watch on all of them for signs of anything that might trigger a major conflagration and for indications of a prematurely violent Trumpian response (the moment to raise a hue and cry). Keeping the spotlight shining on these four potential flashpoints may not be much, but it’s the least we can do to avert Armageddon.