NEW YORK  — Face-to-face for the first time in nearly a year, President Barack Obama and Russian President Vladimir Putin on Monday will confront rising tensions over Moscow’s military engagement in Syria, as well as the stubborn crisis in Ukraine.

Underscoring their deep differences, the U.S. and Russia couldn’t even agree on the purpose of the meeting, which will occur on the sidelines of an annual United Nations summit. The White House said it would focus on Ukraine and getting Moscow to live up to a fragile peace plan. The Kremlin said Ukraine would be discussed only if time allowed, with Syria and the fight against the Islamic State dominating the discussions.

Despite little sign of a breakthrough on either front, U.S. officials insisted it was still worthwhile for the leaders to meet — something that has happened rarely since Obama vowed to isolate Putin in retaliation for Russia’s provocations in Ukraine.

“The president believed it would be irresponsible to let this occasion in which the two leaders would be in the same city pass without trying to test to see whether progress could be made on these newly intractable crises,” Samantha Power, the U.S. ambassador to the United Nations, said Sunday on ABC’s “This Week.”

Ahead of their early evening meeting, Obama and Putin will each have a chance to make their case to a broader audience of world leaders gathered in New York for the United Nations General Assembly. Obama will address the body Monday morning, with Putin following shortly after.