Putin Counted on Waning U.S. Interest in Ukraine. It Might Be a Winning Bet.

President Vladimir V. Putin’s strategy for defeating Ukraine can be summed up in one revealing moment in his February interview with the former television host Tucker Carlson. Addressing the possibility of heightened U.S. involvement in Ukraine, the Russian leader asked Americans: “Don’t you have anything better to do?”

After several tumultuous weeks in American politics, Mr. Putin appears closer than ever to getting the answer he seeks.

President Biden, Ukraine’s most important ally, is engulfed in the biggest political crisis of his tenure, with calls from fellow Democrats to withdraw from the presidential race. Former President Donald J. Trump, favored in the polls, has picked as his running mate one of the loudest critics of American aid to Kyiv.

And at the Republican National Convention Thursday night, Mr. Trump renewed his pledge to end the fighting and channeled Mr. Putin in warning of “World War III.”

All told, the arc of American foreign policy could be moving closer to Mr. Putin’s expectations of it: an inward-looking worldview that cares far less about Ukraine than Russians do, making it only a matter of time until Washington abandons Kyiv like its critics say Afghanistan was abandoned in 2021.

In Moscow, analysts are poring over American polls and news reports, while state television and pro-Kremlin blogs have featured extensive coverage of Mr. Trump’s pick of Senator J.D. Vance as his vice-presidential candidate. Dmitri Trenin, the former head of the Carnegie Moscow Center, said his conclusion from the polling is that “all foreign problems” are low on the priority list for American voters.