U.S. Acting Assistant Secretary of State for East Asian and Pacific Affairs Joseph Yun says the U.S. will readjust its missile defense network in Guam if threats from North Korea dissipate.

Yun made the remark Thursday during a hearing of the U.S. Senate Committee on Foreign Relations’ Subcommittee on East Asian and Pacific Affairs in relation to a statement issued by U.S. Secretary of State John Kerry during his visit to Beijing last weekend.

Kerry said in a meeting with China’s State Councilor Yang Jiechi that there would be no need for the U.S. to boost and forward deploy missile defense networks if North Korea engages in denuclearization. He said the U.S. could reduce its military presence in the Asia-Pacific region if North Korea gives up its nuclear program and the present threat dissipates.

Yun added that the U.S.’s determination to defend South Korea remains firm and stressed that Seoul and Washington will actively work to strengthen their alliance.