President Barack Obama said Friday he was reassessing the 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 convince Russian leader Vladimir Putin to abandon a Cold War mentality.

At a news conference while senior officials from the U.S. and Russia put a brave face on badly strained relations between Washington and Moscow, 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 backwards on those issues, with mixed success,” he told reporters two days after cancelling a planned September summit with Putin. The cancellation was a rare and pointed diplomatic snub over U.S. unhappiness with Russia granting asylum to National Security Agency leaker Edward Snowden, a move that exacerbated already deep differences between Washington and Moscow on other matters.

“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, you know, 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 and that differences could not be completely disguised. But he said U.S.-Russian cooperation is important.

“We’re going to assess where the relationship can advance U.S. interests and increase peace and stability and prosperity around the world,” Obama said. “Where it can, we’re going to keep on working with them, where we have differences, we’re going to say so clearly. And my hope is that, over time, Mr. Putin and Russia recognize that rather than a zero-sum competition, in fact, if the two countries are working together, we can probably advance the betterment of both peoples.”

Obama’s comments came shortly after Secretary of State John Kerry and Defense Secretary Chuck Hagel wrapped up talks with their Russian counterparts that were intended to try to repair some of the damage caused by the differences.

Kerry said that U.S.-Russia ties had been complicated by “the occasional collision” and “challenging moments.” Russian Foreign Minister Sergey Lavrov also acknowledged the fractious state of the relationship but called on both sides to act like “grown-ups,” saying that’s how Moscow wants to handle the differences.

Both men maintained that U.S-Russian cooperation on even limited areas of shared concern is important.

“The relationship between the United States and Russia is, needless to say, a very important relationship, and it is marked by both shared interests and, at times, colliding and conflicting interests and, I think, we are all very clear-eyed about that,” Kerry said. “It’s no secret that we have experienced some challenging moments and obviously not just over the Snowden case. We will discuss these differences today, for certain, but this meeting remains important above and beyond the collisions and moments of disagreement.”

Russia has minced no words in expressing its disappointment that Obama cancelled the summit, and Lavrov made it clear that Moscow had been prepared to sign agreements on trade and nuclear research and security had it gone ahead.

“Of course, we have disagreements. We’ll continue discussing matters on which we disagree calmly and candidly,” he said. “We need to work as grown-ups. And this is what we do. And we hope that this will be reciprocal.”