On Wednesday, President Joe Biden and South Korean President Yoon Suk Yeol will sign the "Washington Declaration," a new agreement to strengthen the U.S. commitment to defend South Korea against nuclear threats from North Korea. The agreement will include plans for U.S. nuclear-armed submarines to dock in South Korea for the first time in more than 40 years, as well as a greater role for South Korea in any response to a potential nuclear attack. The agreement is intended to signal Washington's commitment to deter North Korea from carrying out an attack on its neighbor.