North Korean leader Kim Jong Un ordered his generals to halt from any military activity in the weeks ahead of a summit with President Donald Trump, fearful that any movement would raise tensions and stall talks with the U.S., CNN reports.

The warning was for naught, as Trump walked away from the negotiations in Hanoi, Vietnam, in late February, citing unacceptable sanctions requests by Kim.

Trump said Kim “wanted the sanctions lifted in their entirety, and we couldn’t do that.” In exchange, the North Korean leader had offered to dismantle its main nuclear facility at Yongbyon.

“It wasn’t enough,” the president said at a news conference after the summit collapsed.

Kim, per CNN, thought he could convince Trump to agree to the sanctions.

“He underestimated the president,” an official told the news outlet.

The U.S. presented Kim with evidence of additional secret nuclear sites, surprising the North Koreans, according to Trump. Secretary of State Michael Pompeo said that even without North Korea’s main nuclear facility at Yongbyon the country would still possess missiles, warheads and other elements of a nuclear program that were unacceptable to the U.S.

U.S. officials see no evidence Kim is planning to resume testing missiles.

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