WASHINGTON (AP) — President Donald Trump has raised the possibility that a congressional hearing Democrats arranged with his former personal attorney may have contributed to the lack of results of his summit with North Korean leader Kim Jong Un.

Trump left the summit in Vietnam with the North Korean leader without reaching an agreement last week.

After sending out his National Security Adviser John Bolton to the Sunday talk shows to describe the summit as a success, Trump showed his frustration about the results by lashing out at Democrats.

In a tweet Sunday night, Trump criticized Democrats for holding the congressional hearing with his former lawyer Michael Cohen while he was in sensitive negotiations overseas.

"For the Democrats to interview in open hearings a convicted liar & fraudster, at the same time as the very important Nuclear Summit with North Korea, is perhaps a new low in American politics and may have contributed to the "walk." Never done when a president is overseas. Shame!" Trump tweeted.

As Trump wrapped up his trip to the summit last week, he complained about why Democrats had to hold the hearing at the same time as his negotiations. He described it as a "fake hearing" and said having it in the middle of this "very important summit" was "really a terrible thing." Trump said they could have held it a few days later and had more time to prepare.

During the House Oversight Committee hearing, Cohen was harshly critical of his former boss, calling him a racist, con man and a cheat, during a day of harshly critical comments about Trump.

Bolton earlier Sunday described the summit as a success despite the lack of an agreement providing for verifiable dismantling of the North's nuclear sites. Bolton, in three television interviews, tried to make the case that Trump advanced America's national security interests by rejecting a bad agreement while working to persuade Kim to take "the big deal that really could make a difference for North Korea."

The U.S. and North Korea have offered contradictory accounts of why last week's summit in Vietnam broke down, though both pointed to American sanctions as a sticking point.

In news show appearances, Bolton said the leaders left on good terms and that Trump made an important point to North Korea and other countries that negotiate with him.

"He's not desperate for a deal, not with North Korea, not with anybody if it's contrary to American national interests," Bolton said.

Bolton also sought to explain Trump's comments about taking Kim's word about Otto Warmbier, the American college student who was held prisoner in North Korea, then sent home in a vegetative state. Trump said he didn't believe Kim knew about or would have allowed what happened to Warmbier.

"He tells me that he didn't know about it, and I will take him at his word," Trump said at a news conference last week.

Bolton said Trump's "got a difficult line to walk to" in negotiating with North Korea.

"It doesn't mean that he accepts it as reality. It means that he accepts that's what Kim Jong Un said," Bolton said.

House Minority Leader Kevin McCarthy, R-Calif., a close Trump ally, broke with the president.

"I think Kim knew what happened, which was wrong," McCarthy said.

Some have been critical for Trump letting Kim stand with him on the world stage given North Korea's poor human rights record. Kim will be able to portray himself to his people and supporters as the charismatic head of a nuclear-armed power, not an international pariah that starves its citizens so it can build weapons.

But Bolton said that Trump's view is that he "gave nothing away."

Rep. Adam Schiff, chairman of the House Intelligence Committee, summarized the summit as a "spectacular failure" made all the worse by Trump's comments on "murder of an American citizen, Otto Warmbier."

Bolton said Trump has "turned traditional diplomacy on its head, and after all in the case of North Korea, why not? Traditional diplomacy has failed in the last three administrations."

An example of that non-traditional diplomacy was formally unveiled Sunday when South Korea and the U.S. announced they would not conduct massive springtime military drills and were replacing them with smaller exercises. They described it as an effort to support diplomacy aimed at resolving the North Korean nuclear crisis.

"The reason I do not want military drills with South Korea is to save hundreds of millions of dollars for the U.S. for which we are not reimbursed," Trump tweeted Sunday. "That was my position long before I became President. Also, reducing tensions with North Korea at this time is a good thing!"

Bolton spoke on "Fox News Sunday," CNN's "State of the Union" and CBS's "Face the Nation." McCarthy was on ABC's "This Week," and Schiff was on CBS.