An official claimed that a US nuclear missile submarine would visit South Korea for the first time in decades as part of a strengthened nuclear shield to be revealed at the White House by Presidents Joe Biden and Yoon Suk Yeol. 

According to a senior US official, the actions outlined on Wednesday are unprecedented since the Cold War and are intended to increase deterrence in the face of North Korea's nuclear operations. 

Biden and Yoon will release the Washington Declaration during their state visit to the White House, explaining how, in addition to a strengthened US military umbrella, the US would expand information exchange with Seoul. 

The agreement, in response to rising tensions over North Korea's missile launches and nuclear weapons, mirrors actions seen last seen when Washington managed Europe's strategic defense against the Soviet Union. 

A senior official stated ahead of the Biden-Yoon meeting that "the United States has not taken these steps, really, since the height of the Cold War with our very closest handful of allies in Europe. And we are seeking to ensure that by undertaking these new procedures, these new steps, that our commitment to extended deterrence is unquestionable."

Officials speaking on the condition of anonymity said there are no plans to post US nuclear weapons in South Korea, a departure from the Cold War when US strategic weapons were stationed in Europe. In addition, Seoul will restate its vow not to seek its own nuclear weapons. 

Despite heavy international sanctions over its weapons programs, Pyongyang has built up an arsenal of intercontinental ballistic missiles (ICBMs). According to the South Korean Defense Ministry, DPRK's test launches are part of the country's efforts to boost space reconnaissance capabilities.

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According to a senior official, "We'll announce that we intend to take steps to make our deterrence more visible through the regular deployment of strategic assets, including a US nuclear ballistic submarine visit to South Korea, which has not happened since the early 1980s."

"We'll strengthen our training, our exercises, and simulation activities to improve the US-ROK alliances approach to deterring and defending against DPRK threats, including by better integrating ROK conventional assets into our strategic planning," the official added.

Aside from submarines, there would be a "regular cadence" of other significant assets, "including bombers or aircraft carriers," according to the official. However, there will be "no basing of those assets, and certainly not nuclear weapons." 

Despite increased cooperation and preparation, a US official emphasized that the use of American nuclear weapons remains solely within the authority of the US president. 

According to one official, preparations are being made ahead of time to ease any possible concerns with Beijing over the harsher military posture. 

"We are briefing the Chinese in advance and laying out very clearly our rationale for why we are taking these steps," the official explained, adding that the Biden administration is "disappointed that China has been unprepared to use its influence" on North Korea. 

Yoon is just the second foreign leader to be invited to the White House for a state visit by Biden, and he and his wife were to be received with full military honors. Before conducting a news conference in the Rose Garden, the two presidents were talking in the Oval Office. 

As South Korea weaves closer ties with the US, DPRK's leader declared last year that his country is an "irreversible" nuclear power, conducting weapon tests nearly every month, including the launch of its most advanced intercontinental ballistic missile (ICBM).