If Russia does invade Latvia or one of the other Baltic States, of course, the United States and its allies would have to fight — and fight hard — to defend them. These countries are members of NATO and the European Union. To surrender them to Russian aggression would make the West look both morally bankrupt and geopolitical impotent. But it is hard to imagine any realistic situation in which this need will arise.

Eastern Europe is not the only arena where the American agenda has proved inept. In Syria, the United States and Western Europe have bungled the war. Here, too, Mr. Trump’s plans to cooperate with Russia would be a welcome change. Because of Russian, Iranian and now Turkish support, Mr. Assad’s Syrian state is not going to fall. If it is to be transformed in the future, negotiation with Russia and Iran will be necessary.

Iran is an essential ally against the jihadists in Iraq and Syria. And that means that the White House will soon discover the dangerous inconsistencies in its policies. Both Mr. Trump and his recently resigned national security adviser, Michael T. Flynn, have spoken of prioritizing the fight against the Islamic State. But by simultaneously expressing desire for a new confrontation with Iran, they have demonstrated that they do not actually understand the word “priority.”

Furthermore, barring an open Iranian violation of the nuclear agreement, no imaginable American concession to Russia would persuade Moscow to agree to new international sanctions against Iran. One reason is that Russia sees good relations with Iran as permanently in its interest, whereas the policy makers in Moscow know that American concessions may be withdrawn by the next administration.

China may be the other major sticking point. While he has moderated his stand somewhat in recent weeks, Mr. Trump has suggested he is prepared for a confrontation with China. But Russia will not play along. With a 2,600-mile-long border with China and a hopelessly outnumbered army, there is no way that Russia can be persuaded to adopt an outright hostile stance toward its neighbor. The furthest that Russia might go as a result of a better relationship with the United States would be to limit sales of its most sophisticated weapons to China, and perhaps to help seek a United Nations-brokered international compromise over the islands disputed by China and its neighbors.

Since the end of the Cold War, Russia has not opposed the United States out of blind anti-Americanism. In the former Soviet countries, Russia has defended what the Russian establishment sees — rightly or wrongly — as vital Russian national interests.

Elsewhere in the world, Russia has clashed with the United States for reasons that have often been shared by many Americans, and have often later been proved correct: opposition to the invasion of Iraq and the overthrow of Col. Muammar el-Qaddafi’s regime in Libya being the most notable examples. While Russia wants good relations with the United States, it will not lend blanket support to American global primacy. If that is what the Trump administration is hoping for, it will be sorely disappointed, and the latest attempt at reconciliation with Russia will fail.