Michael Mullen
Michael MullenReuters

Michael Mullen, the former Chairman of the Joint Chiefs of Staff, warned on Sunday that the United States faces a greater threat of nuclear conflict on the Korean peninsula than at any previous time.

"We're actually closer in my view, to a nuclear war with North Korea and in that region than we have ever been," Mullen, who served under Presidents George W. Bush and Barack Obama, told ABC News "This Week".

"I don't see the opportunities to solve this diplomatically at this particular point," he added.

Mullen, who chaired the Joint Chiefs from 2007 to 2011, said President Donald Trump has succeeded in getting China to take a more active role in trying to restrain North Korea's nuclear activities.

“I think President Trump has made China move more than they have in the past. Whether they continue to do that to help resolve this is the open question,” he said adding, “A real measure of how this all comes out is whether China is going to commit to a peaceful resolution here. If they don't, then I worry a great deal that it's much more likely there will be conflict.”

At the same time, Mullen also said that Trump has disrupted long-held views of the U.S. role in the world, and that America’s enemies benefit from that uncertainty in "an incredibly dangerous climate."

The Trump presidency has been “incredibly disruptive, certainly unpredictable in many many ways,” he told ABC News, adding, “Those who have been our friends for many years ask questions about our commitments to them...and our enemies, those that would do us ill, seem to be able to take advantage of the uncertainty.”

Tensions on the Korean peninsula have risen markedly in recent months after North Korea’s latest missile and nuclear tests, conducted in defiance of international pressure and United Nations resolutions.

Most recently, North Korea launched a Hwasong-15 missile, a new type of intercontinental ballistic missile (ICBM) which officials said can fly over 13,000 km (8,080 miles).

Pyongyang said following the launch that it had test-fired its most advanced missile, putting the U.S. mainland within range, and also declared itself to be "a responsible nuclear power"

Trump has in the past threatened to "totally destroy" North Korea if it attacks the United States while North Korea insists the world must now accept that it is a nuclear power.

While U.S. Secretary of State Rex Tillerson has said Washington is open to dialogue with North Korea, an unconfirmed report this week indicated that the United States is drawing up plans for a “bloody nose” military attack on North Korea to stop its nuclear weapons program.

Mullen said in his remarks Sunday that he is also concerned about a possible nuclear threat from Iran if Trump ends the Iran nuclear agreement.

If Trump makes good on his campaign promise to end the deal, Iran could rapidly develop nuclear weapons, he warned.

“I worry greatly about the fact that the Iranians will bring forward a nuclear weapon capability,” Mullen said. “They were very close when the deal was struck. They can redevelop it, I think, very rapidly.”

Trump in October decided not to certify that Tehran is complying with the 2015 nuclear deal, leaving its fate to Congress.