President Barack Obama is canceling his planned meeting Russian President Vladimir Putin scheduled for next month in Moscow, an administration official said on Wednesday.
The Obama administration has repeatedly expressed disappointment after Moscow granted asylum to former U.S. spy agency contractor Edward Snowden, rejecting pleas to hand him over to face espionage charges.
The president is still expected to attend the G20 summit in Russia this fall.
Speaking on NBC's "The Tonight Show" with host Jay Leno, Obama said Moscow sometimes slipped into a Cold War mentality, despite being cooperative with the United States on some issues, including counterterrorism efforts in the aftermath of the Boston Marathon bombing.
Washington wants Snowden, who was in hiding in Hong Kong before flying to Moscow in June, to be returned to the U.S. to be prosecuted for disclosing secret American Internet and telephone surveillance programs.
"What I say to President Putin is, that's the past and ... we've got to think about the future. And there's no reason why we shouldn't be able to cooperate more effectively than we do."
During the interview, Obama also said the recent threat that caused the United States to close its embassies throughout the Middle East was significant.
"It's significant enough that we're taking every precaution," Obama said.
"It's a reminder that for all the progress we've made ... this radical, violent extremism is still out there," Obama said. "We've got to stay on top of it."
The U.S. State Department issued a worldwide travel alert Friday warning Americans that al Qaeda may be planning attacks in August, particularly in the Middle East and North Africa. It initially announced the embassy closures would be only for Sunday, then extended the closures of some by a week.
Asked whether the controversial surveillance programs helped lead to the intelligence that sparked the warnings, Obama said the programs were critical to counterterrorism work. But he said more needed to be done to assure Americans they were not being spied on themselves.
"We don't have a domestic spying program," he said. "What we do have are some mechanisms where we can track a phone number or an email address that we know is connected to some sort of terrorist threat."
The odds of dying in a terrorist attack were less than dying in a car accident, Obama said, and Americans should be careful but did not need to cancel planned vacations to places such as Europe as a result of the recent travel warnings.
In lighter notes, Obama said he had invited his former secretary of state, Hillary Clinton, to her recent lunch at the White House and described her as having a post-administration "glow."
"We have become genuinely close, and I could not have more respect for her," Obama said.
Asked by Leno whether the former first lady and potential 2016 presidential candidate had "measured the drapes" while she was there, Obama said no.
"Keep in mind she's been there before," he joked. "She doesn't have to measure them."
Obama also confirmed — more or less — a budding "bromance" with his former 2008 presidential rival, Republican Sen. John McCain, who has been supportive of Obama's push to reform U.S. immigration laws.
"That's how a classic romantic comedy goes, right? Initially you're not getting along and then you keep on bumping into each other," Obama joked.
"John McCain and I have, you know, a number of philosophical differences, but he is a person of integrity. He is willing to say things regardless of the politics."
Leno also poked fun at Obama for having told a group of young people that broccoli was his favorite food.
"Me and broccoli, I don't know, we've got a thing going," Obama offered.