President Trump and Japanese Prime Minister Shinzo Abe spoke by phone Saturday on ways to "maximize pressure" on North Korea over its missile program, the White House announced.

Trump and Abe "reaffirmed the importance of close cooperation between the United States, Japan, and South Korea in the face of the growing threat from North Korea," the White House said.

Trump also noted that he "looks forward to continued trilateral coordination" on the sidelines of the United Nations General Assembly later this month in New York.

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The call came Saturday as North Korean state media announced that the country had developed a hydrogen bomb that it says it plans to load onto an intercontinental ballistic missile (ICMB).

North Korea launched a missile over Japan earlier this week, signaling to the U.S. and its allies that the country would not back down from its aggressive actions.

Trump responded to the action in a tweet saying dialogue with Pyongyang was no longer "the answer."

The U.S. has been talking to North Korea, and paying them extortion money, for 25 years. Talking is not the answer! — Donald J. Trump (@realDonaldTrump) August 30, 2017

Despite the heightened tensions in the region, Trump on Saturday confirmed that he was speaking with advisers about the future of the United States' free-trade agreement with South Korea.

Several reports indicated that the Trump administration was eyeing a withdrawal from the deal, with a push to formally begin the withdrawal process starting as early as Tuesday.

Such a move could create economic tension between Washington and Seoul. The U.S. and South Korea conducted joint military exercises in the face of North Korean aggression last month.