North Korea is world's most dangerous problem, says former US Defense secretary

For North Korea, no good options left: William Cohen

The world has exhausted all options for dealing with North Korea and the situation cannot be resolved until there's a change in the regime's direction, or a change in the regime, former United States Defense Secretary William Cohen told CNBC Monday.

"There are no good options that are available right now, we've tried them all. I've been, over the years, involved in the six-party talks in seeing if we could find a way to work together, but it's always one step forward, two back," Cohen said at the sidelines of the China Development Forum in Beijing.

"That would be the most difficult issue to resolve. I think that's the most dangerous issue we have facing us today. Kim Jong Un seems dedicated to being even more provocative, more aggressive," he added.

A sales assistant watches TV sets broadcasting a news report on North Korea's nuclear test, in Seoul, January 6, 2016.
Kim Hong-Ji | Reuters

Geopolitical tensions heightened in recent weeks after North Korea launched ballistic missiles into the Sea of Japan and tested a new type of high-thrust rocket engine. The potential deployment of a U.S. anti-missile system in South Korea saw China retaliating against Seoul.

However, Cohen, who is chairman and CEO of the Cohen Group, said President Donald Trump has put together a good national security team. People such as Secretary of Defense Jim Mattis and Secretary of State Rex Tillerson are people who could offer good advice in dealing with the North Korea situation, he said.

We all want a better relationship with Russia: Cohen

It is then up to Trump on whether he would act on the advice he is given.

"If you look at the people you've put in there, mostly people in the military in the national security team, that's good, because the military men are the last ones that want to go to war… So I'm encouraged, I think we need to give President Trump some time, and again this is new for him, he's had no government experience. So things that you could say in the past don't go over quite as well in that Oval Office," Cohen said.

On U.S.-Russia relations, Cohen, who once expressed concerns about Trump, said the situation would not improve until the president clarifies his companies' financial ties with Russia.

There's a cloud hanging over the Trump administration saying, 'What is the nature and basis of this bromance?'
William Cohen
former United States Defense Secretary, on Trump and Putin

The two countries have had a volatile relationship, which has included U.S. sanctions on the country. Many observers have said that U.S.-Russia relations have recently regressed to levels of hostility not seen since the Cold War era.

"There's a cloud hanging over the Trump administration saying, 'What is the nature and basis of this bromance?' Namely that you could embrace Putin given what he's done in Crimea, given the fact he's tried to destabilize Ukraine, given the fact he's tried to cause some anxiety in the Baltic, et cetera, and it's inexplicable at this point, so I think he's going to have to be more forthcoming," he said.

"The president should be asked three questions: Number one, what do you own? Number two, what do you owe? And number three, to whom do you owe it? And if you resolve those issues then you remove the cloud, saying we all want a better relationship with Russia," he added.

Follow CNBC International on Twitter and Facebook.