WASHINGTON — President Barack Obama said Friday he was reassessing the U.S. relationship with Russia because of a growing number of issues on which the two countries differ, and he lamented what he called his mixed success in trying to persuade Russian leader Vladimir Putin to abandon a Cold War mentality.

Obama’s comments at a White House news conference just two days after cancelling a planned summit with Putin came as senior U.S. and Russian officials met to look at areas in which cooperation is possible.

Those officials put a brave face on the badly strained ties and said the meeting produced some tangible results on the military front and on the push to forge a political solution to the crisis in Syria, among other issues.

Obama said Putin’s return to the Kremlin last year had brought about “more rhetoric on the Russian side that was anti-American, that played into some of the old stereotypes about the Cold War contest between the United States and Russia.”

“I’ve encouraged Mr. Putin to think forward as opposed to backward on those issues, with mixed success,” he told reporters. He said he decided not to attend the summit because “Russia has not moved” on a range of issues. He said his unhappiness with Russia granting asylum to NSA leaker Edward Snowden was one reason, but not the only one, for his decision.

“I think the latest episode is just one more in a number of emerging differences that we’ve seen over the last several months around Syria, around human rights issues where ... it is probably appropriate for us to take a pause, reassess where it is that Russia’s going, what our core interests are, and calibrate the relationship so that we’re doing things that are good for the United States and, hopefully, good for Russia,” Obama said.

He added that no one could hope for 100 percent agreement. But he said U.S.-Russian cooperation is important.

Obama praised trade and arms control successes that the U.S. and Russia were able to seal when he was dealing with former Russian President Dmitry Medvedev. Obama played down suggestions that he and Putin do not get along.

“I don’t have a bad personal relationship with Putin. When we have conversations, they’re candid. They’re blunt. Oftentimes, they’re constructive,” he said.

But, he took a shot at the often dour-looking Russian leader for his demeanor and appearance.

“He’s got that kind of slouch, looking like the bored kid in the back of the classroom,” Obama said. “But the truth is, ... when we’re in conversations together, oftentimes it’s very productive.”

He urged Putin to not view the United States as an enemy.

“If issues are framed as if the U.S. is for it, then Russia should be against it, or we’re going to be finding ways where we can poke each other, then probably we don’t get as much stuff done,” Obama said.