Mike Mullen, former chairman of the Joint Chiefs of Staff, said his "concern is how long that actually lasts," in regards to how long President Trump will listen to the advice of his top advisers. Mullen: Threat of nuclear war with North Korea heightened

Mike Mullen, former chairman of the Joint Chiefs of Staff, said Sunday that the U.S. is closer to nuclear war with North Korea than ever before, an example of America's adversaries taking advantage of the "uncertainty" of President Donald Trump's leadership.

"Those that would do us ill seem to be able to take advantage of the uncertainty as well, and you mentioned both Russia and China, and my expectations that will continue to be the case for them as well as Iran and North Korea," Mullen told Martha Raddatz on ABC's "This Week."


"We're actually closer, in my view, to a nuclear war with North Korea and in that region than we have ever been."

Mullen, a retired admiral who served as chairman under both President George W. Bush and Barack Obama, said he has watched top administration officials like national security adviser H.R. McMaster, Defense Secretary James Mattis and White House chief of staff John Kelly try to quell some of the uncertainty by getting the president to make decision that go against his instinct.

But Mullen is not sure if such a approach is sustainable.

"My concern is how long that actually lasts," he said.

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The long-term question, Mullen said is whether the American people continue to support the institutions and norms that he sees Trump undermining — an approach that has led to some of the uncertainty that North Korea, Russia and other countries are taking advantage of.

Outside of his criticism of the current president, Mullen hinted at lingering tension over Obama's handling of Iranian protests in 2009. In light of current unrest in the country, some commentators have said the administration should have been more vocal about its support for the protesters then and not have put so much stock in building diplomatic ties with Iranian leaders.

Trump and his administration have been vocal in their pronouncements that the "world is watching" Iran and whether it or not it respects the rights of protesters voicing their frustration with the country's economy.

"I think that the 2009 time frame is very instructive," Mullen said. "I think we chose to not be as supportive as we could have been then. And I hope we can be right now so that Iran can continue to evolve."