Barack Obama used his first appearance as president at the General Assembly this week to tell the rest of the world to stop complaining about US hegemony and start working with Washington on big global problems. “Make no mistake: this cannot be solely America’s endeavor,” President Obama told the General Assembly. “Those who used to chastise America for acting alone in the world cannot now stand by and wait for America to solve the world’s problems alone.”

He will have to take some of his own advice in coming months; it is the United States that has been dragging its feet in on the hot-button topics of energy consumption and nuclear nonproliferation.

If various nations have used grievances against the United States as an excuse to do nothing themselves, as Obama suggested, the political truth around the United Nations is that too often not much gets accomplished until there is leadership not only from Washington but also in Washington on issues that matter to others beyond American shores.

Certainly much of the catch-up work that the Obama administration faces is inherited, not only from the George W. Bush years but also from Bill Clinton’s second term, when the White House ran scared of a right-wing surge in Congress and its misplaced patriotic isolationism. Piling a push for an energy bill and nuclear-test-ban treaty ratification onto an already full agenda may renew criticism in domestic politics that Obama is trying to do too much too soon.

On Tuesday, speaking to a gathering of world leaders invited by Secretary General Ban Ki-moon to exchange ideas about climate change in advance of a landmark summit in Copenhagen in December on curbing emissions, Obama took credit for what the United States was already accomplishing domestically. He could not promise, however, that he could go to Copenhagen with a national energy bill in hand, whether or not such a law would even meet the world’s expectations.

The Europeans were blunt in their reaction. “Asking an international conference to sit around looking out the window for months, while one chamber of the legislature of one country deals with its other business, is simply not a realistic political position,” the European Union’s ambassador to the United States, John Bruton, told Roger Nokes, writing in the online World Bulletin of the United Nations Association of the USA.

Still more complex and difficult for Obama will be building momentum for expanding and strengthening international agreements controlling nuclear weapons. This job starts in Washington, with the long-overdue ratification of the 1996 Comprehensive Test Ban Treaty (CTBT), but it does not stop there.

The CTBT–which bans all nuclear weapons testing on land or sea, in the atmosphere, underwater and underground–requires more than just signing and ratification by a majority of nations. It has already been signed by 181 countries of the UN’s 192 members, and ratified by 150 of them. The hitch is that forty-four nations that had nuclear technology in place when the treaty was written thirteen years ago must sign and ratify it before it can enter into force. So far only thirty-five of them have met the requirement. Nine nuclear countries have not signed and/or ratified: China, Egypt, India, Indonesia, Iran, Israel, North Korea, Pakistan and the United States.

Obama and his nonproliferation team will have to do more than just prod the Senate into action on the CTBT, which Bill Clinton was reluctant to do after the United States signed the pact. Washington will have to put huge diplomatic muscle into corralling countries where it has leverage, starting with Israel, India and Pakistan. This looks like an impossible task.

The same daunting challenge confronts Obama’s promised efforts to get universal acceptance of the 1968 treaty on the nonproliferation of nuclear weapons, the Nuclear Nonproliferation Treaty (NPT), and to close critical loopholes. Here again there are some of the same nonsignatories among countries with nuclear weapons, most notably Israel, India and Pakistan. (North Korea and Iran signed the treaty, though North Korea’s membership is in limbo). The fact that Iran is in the international hot seat should not obscure the fact that in both India and Pakistan, not to mention Israel, there is no international inspection of weapons-grade programs.

For months, Obama administration officials have been saying that the United States will lean on countries that have not signed the NPT to do so. India will resist mightily, calling in its influential lobbies in Washington, which helped push Congress into approving a nuclear technology deal with the Indians that a number of leading US arms control experts saw as a death blow to international treaties and nonproliferation generally. Pakistan will never sign until India does.

On Thursday, Obama chaired a meeting of the UN Security Council–the first American president to do so–that passed a unanimous US-drafted resolution calling for “a world without nuclear weapons.” In his remarks to the council, Obama called the spread of nuclear arms “a fundamental threat to the security of all peoples and all nations.”

For most UN member nations, the Security Council’s own five permanent members–Britain, China, France, Russia and the United States–should start by setting a better example for arms reductions. The new resolution calls for new steps in disarmament, and the Americans and Russians, who have already cut arsenals in recent decades, are pledging to continue arms-reduction talks. Obama told the Security Council that the coming year will be critical for global disarmament. He plans to hold a summit in Washington in April ahead of an NPT review conference in May.

Still, Mohamed ElBaradei, the outgoing head of the International Atomic Energy Agency, the world’s nuclear watchdog, was quoted by the Reuters news agency as saying that Security Council resolutions notwithstanding, the big powers have a long way to go. Only by demonstrating an irreversible commitment to disarming, ElBaradei said, can the nuclear powers “gain the moral authority to call on the rest of the world to curb the proliferation of these inhumane weapons.”