President Trump has instructed advisers to prepare a withdrawal from the U.S. free-trade agreement with South Korea, several people close to the process said, a move that would stoke economic tensions with the U.S. ally at a time when both countries confront a crisis over North Korea’s nuclear weapons program.

While it is still possible Trump could decide to stay in the agreement in order to renegotiate its terms, the internal preparations for terminating the deal are far along and the formal withdrawal process could begin as soon as this coming week, the people said.

A number of senior White House officials are trying to prevent Trump from withdrawing from the agreement, including national security adviser H.R. McMaster, Defense Secretary Jim Mattis, and National Economic Council Director Gary Cohn, the people said.

A White House spokeswoman said “discussions are ongoing, but we have no announcements at this time.”

South Korea elected a new president, Moon Jae-in, in May, and Trump has been frustrated that Moon is not willing to accept the initial U.S. trade demands, several trade experts said. Foreign leaders at first worked hard to try to build strong relations with Trump, but there has been a marked change in recent months with numerous leaders standing up to his brand of nationalism.

‘PLAYING WITH FIRE’

Trump is “playing with fire,” said Gary Schmitt, co-director of the Marilyn Ware Center for Security Studies at the American Enterprise Institute. “There is a new president in South Korea whose instincts probably are to be probably not as pro-America as his predecessor and now you are putting him in situation where he has to react. In fact, what you need now is as much cooperation as possible.”

One reason top White House advisers are trying to stop Trump from withdrawing from the South Korea free trade agreement is because they do not want to isolate the government in Seoul at a time when North Korea has become increasingly adversarial with its missile program, testing nuclear weapons and firing missiles over Japan in a way that has alarmed the international community.

If Trump withdraws from the agreement, he could try to force South Korea to import more U.S. products with little to no import restrictions, something he believes will help U.S. companies and workers. South Korea could also decide to refuse any discussions with Trump, kicking off a trade war between the countries.

The trade agreement was signed in 2007 and went into effect in 2012.

Withdrawing from the deal could lead to a large increase on tariffs levied against products the United States imports from South Korea, such as electronics, cellphones and automobiles. South Korea would also immediately start charging high tariffs on goods and services imported into its country. Chad Bown, who served as an economist in the White House during the Obama administration, said the tariff the U.S. government charges against many Korean imports would rise from 0 to 3.5 percent. The tariff South Korea charges against U.S. imports would rise from 0 to almost 14 percent.