During South Korean President Yoon Suk Yeol's visit to the White House, President Joe Biden renewed America's commitment to protecting South Korea in the face of ongoing nuclear threats from North Korea. The emphasis of this renewed commitment is on "extended deterrence," which means that the United States will use its nuclear arsenal if necessary to respond to a North Korean nuclear attack on the South. This emphasis highlights the failure of previous efforts to disarm North Korea and serves to calm concerns in South Korea that they may need their own independent arsenal as protection. The North's rapid expansion of nuclear capabilities is a source of perpetual concern for both countries. The "Washington Declaration," a set of new steps to strengthen US-South Korean cooperation on military training, is expected to be announced during the visit. It includes new commitments to bolster extended deterrence and the regular deployment of strategic assets, including potentially a US nuclear ballistic submarine visit to South Korea.