President Trump will address global leaders at the United Nations General Assembly in New York on Tuesday morning as he is confronted with a deeply unpopular war in Iran and rising concerns about the unpredictability of artificial intelligence. In addition to a series of global crises, Mr. Trump is also juggling a packed schedule. After delivering his address, the president is expected to meet with leaders of Britain, Japan, Venezuela and a number of Persian Gulf nations.

He is also expected to sign an agreement with Denmark and Greenland that Mr. Trump says will expand the U.S. security presence in the semiautonomous Danish territory. The signing comes after Mr. Trump this year demanded total control of Greenland, a threat that prompted intense criticism from allies who will be at the opening of the United Nations session in New York. Mr. Trump will again face a United Nations that he has long derided as outdated, inefficient and beholden to powers that revel in defying American wishes. But this year, more than most, he is increasingly isolated on the world stage.

Instability in the Middle East remains a pressing issue. Mr. Trump will join members of the Gulf Cooperation Council, which includes the U.S. allies Saudi Arabia, Qatar, the United Arab Emirates, Kuwait, Bahrain and Oman. The nations in the Gulf region are likely to raise concerns about soaring energy prices caused by the fallout of the war in Iran, which has shown little sign of ending. Mr. Trump will argue in his speech that the war in Iran is necessary to prevent the nation from having a nuclear weapon. Frayed Alliances Mr. Trump enters the summit with a track record of attacking, rather than uniting, many of the attendees.

He has attacked many European leaders for not supporting the U.S.-Israeli war in Iran. His threats to take over Greenland nearly upended the Western alliance and in part prompted Prime Minister Mark Carney of Canada to warn of a rupture in the world order. The United States and Canada are still locked in a trade war. Mr. Trump met with France's president, Emmanuel Macron, at Trump Tower on Monday, and it remains to be seen how Mr. Trump will approach his first meeting with Britain's new prime minister, Andy Burnham.

But the introduction will come after Mr. Trump weighed in on a highly divisive subject this month by endorsing the unification of the Republic of Ireland and Northern Ireland, which is still part of the United Kingdom.