WASHINGTON/BEIJING (Reuters) - President Donald Trump warned on Wednesday that the United States would no longer tolerate North Korea’s actions but said the use of military force against Pyongyang will not be his “first choice.”

His comment appeared to be in line with classified briefings to Congress in which Trump’s top national security aides - Defense Secretary Jim Mattis, Secretary of State Rex Tillerson and Dan Coats, the director of national intelligence - stressed the search for a diplomatic solution to the crisis, lawmakers said.

A senior administration official, meanwhile, said that the White House has set aside for now consideration of exiting a free trade pact with South Korea, a move being contemplated by Trump that could have complicated relations with Seoul.

In a flurry of phone calls with world leaders days after North Korea’s sixth and most powerful nuclear test, Trump and Chinese President Xi Jinping committed to “take further action with the goal of achieving the denuclearization of the Korean peninsula,” the White House said.

“President Xi would like to do something. We’ll see whether or not he can do it. But we will not be putting up with what’s happening in North Korea,” Trump told reporters, though he offered no specifics.

“I believe that President Xi agrees with me 100 percent,” he added.

Asked whether he was considering a military response to North Korea, Trump said: “Certainly, that’s not our first choice, but we will see what happens.”

Xi, who has been under pressure from Trump to do more to help curb North Korea’s nuclear and missile programs, told the U.S. president during their 45-minute call that the North Korean issue must be resolved through “dialogue and consultation.”

The focus on negotiations by China, North Korea’s main trading partner, contrasted with Trump’s assertions over the last few days that now was not the time for talks with North Korea while pressing instead for increased international pressure on Pyongyang.

The United States and South Korea have asked the United Nations to consider tough new sanctions on North Korea after its nuclear test on Sunday that Pyongyang said was an advanced hydrogen bomb.

Late on Wednesday, U.S. Treasury Secretary Steve Mnuchin indicated that if the U.N. Security Council fails to approve sufficiently strong measures, Trump could authorize him to impose sanctions on any country or entity that trades with North Korea.

“We believe that we need to economically cut off North Korea,” Mnuchin told reporters aboard Air Force One as it flew back from North Dakota, where Trump gave a speech on tax reform. “I have an executive order prepared. It’s ready to go to the president. It will authorize me to . . . put sanctions on anybody that does trade with North Korea.”

Mnuchin said that Trump would consider the order “at the appropriate time once he gives the U.N. time to act.”

He provided no further details, including whether Trump would consider slapping sanctions on China, North Korea’s largest trade partner.

Russian President Vladimir Putin insisted on Wednesday that resolving the North Korean nuclear crisis was impossible with sanctions and pressure alone.

Putin met South Korea’s Moon Jae-in on the sidelines of an economic summit in the eastern Russian city of Vladivostok amid mounting international concern that their neighbor plans more weapons tests, including possibly a long-range missile launch before a weekend anniversary.

Putin echoed other world leaders in denouncing North Korea’s latest nuclear bomb test on Sunday, saying Russia did not recognize its nuclear status.

“Pyongyang’s missile and nuclear program is a crude violation of U.N. Security Council resolutions, undermines the non-proliferation regime and creates a threat to the security of northeastern Asia,” Putin said at a news conference.

“At the same time, it is clear that it is impossible to resolve the problem of the Korean peninsula only by sanctions and pressure,” he said.

No headway could be made without political and diplomatic tools, Putin said.

Slideshow ( 16 images )

MOON SEEKS SANCTIONS

Moon, who took office this year advocating a policy of pursuing engagement with North Korea, has come under increasing pressure to take a harder line.

He has asked the United Nations to consider tough new sanctions after North Korea’s latest nuclear test.

The United States wants the Security Council to impose an oil embargo on North Korea, ban the country’s exports of textiles and the hiring of North Korean laborers abroad and subject leader Kim Jong Un to an asset freeze and travel ban, according to a draft resolution seen by Reuters on Wednesday.

Diplomats say the U.N. Security Council could also consider barring the country’s airline.

“I ask Russia to actively cooperate as this time it is inevitable that North Korea’s oil supply should be cut at the least,” Moon told Putin, according to a readout from a South Korean official.

Slideshow ( 16 images )

Putin said North Korea would not give up its nuclear program no matter how tough the sanctions.

“We too, are against North Korea developing its nuclear capabilities and condemn it, but it is worrying cutting the oil pipeline will harm the regular people, like in hospitals,” Putin said, according to the South Korean presidential official.

Russia’s exports of crude oil to North Korea were tiny at about 40,000 tonnes a year, Putin said. By comparison, China provides it with about 520,000 tonnes of crude a year, according to industry sources.

Last year, China shipped just over 96,000 tonnes of gasoline and almost 45,000 tonnes of diesel to North Korea, where it is used across the economy, from fishermen and farmers to truckers and the military.

Trump and British Prime Minister Theresa May agreed in a telephone call on Tuesday that China must do more to persuade North Korea to cease its missile tests, a spokesman for May said.

‘FREEZE FOR FREEZE’

Sanctions have done little to stop North Korea boosting its nuclear and missile capacity as it faces off with Trump, who has vowed to stop it from being able to hit the U.S. mainland with a nuclear weapon.

China and Russia have advocated a “freeze for freeze” plan, where the United States and South Korea stop major military exercises in exchange for North Korea halting its weapons programs, but neither side is willing to budge.

North Korea says it needs to develop its weapons to defend itself against what it sees as U.S. aggression.

South Korea and the United States are technically still at war with North Korea after the 1950-53 Korean conflict ended with a truce, not a peace treaty.

China objects to both the military drills and the deployment in South Korea of an advanced U.S. missile defense system that has a radar that can see deep into Chinese territory.

South Korea’s Defence Ministry said the four remaining batteries of the Terminal High Altitude Area Defense (THAAD) system would be deployed on a golf course in the south of the country on Thursday. Two THAAD batteries have already been installed.

For a graphic on nuclear North Korea, click: here