At his summit with North Korean leader Kim Jong Un, U.S. President Donald Trump could be aiming to rid the isolated country of its massive chemical and biological weapons stockpile, according to U.S. Ambassador to Japan William Hagerty — a move that suggests a push to go beyond the long-standing focus on Pyongyang's nuclear weapons.

"We had broad-ranging discussions on the topic, and it extended beyond denuclearization to the topics of chemical and biological weapons as well," Hagerty said during a telephone conference Thursday with reporters following the two-day summit between Trump and Prime Minister Shinzo Abe at the U.S. president's Mar-a-Lago estate in Florida. Hagerty was part of the presidential delegation attending the summit.

"The president's intention is to see all of these weapons of mass destruction eliminated from the Korean Peninsula, and the strategy remains the same in terms of complete, verifiable and irreversible aspects of denuclearization," he said.