Sometimes you get an assist from the most unlikely of people. That is what happened on Sunday when a former member of President Obama’s administration gave credit to President Donald Trump for his work on North Korea.

Former Defense Secretary Robert Gates told CBS’ “Face The Nation” host Margaret Brennan that it was the president’s “unpredictability” that has caused North Korean dictator Kim Jong Un to cave.

“I think that the unpredictability in terms of some of the tweets and some of the tough talk did get the attention of the North Koreans and the Chinese as well — in terms of fire and fury and so on. You know, my view is generally that tactical unpredictability is good and as an asset; strategic unpredictability is probably not a good idea for a great power,” he told Brennan.

He said he was not certain which unpredictability the president has, tactical or strategic, but he did say what he thinks President Trump should do when he meets with Kim Jong Un at the highly anticipated summit on June 12.

“I think the president goes in with a lot of cards to play. A peace treaty. Diplomatic recognition. A guarantee that the United States would not try and overthrow the regime by force. The whole panoply of economic sanctions that have been put on. So, he has a lot to negotiate with. And the question is how you move the ball forward in a way that — that extracts from the North genuine movement in these areas and that isn’t reversible, as we saw with the 1994 agreement and so on – and that’s the key,” he said.

“So I think the two — the two things to watch out for, if you will, are — are agreements where the North Koreans could reverse themselves at relatively little cost. And the second is some kind of an agreement that leaves the South Koreans and the Japanese out in the cold. And — and I think we can’t underestimate Kim’s interest in splitting, particularly South Korea off from the United States, but perhaps even Japan. So I think those are the things to be particularly concerned about,” Gates said.

He said that whatever agreement is made with the North Koreans it should be ratified in a treaty because a deal done by executive fiat, like former President Obama’s Iran nuclear deal, can be undone by the next president if it is not ratified by Congress.

“We’ve seen with the Iran deal — if you — if you just do these things by executive agreement, first of all that doesn’t make it the law of the land for the next president. The next president, with the stroke of a pen, can overturn it, just as President Trump has done with the Iran deal,” he said.