Usa news: The US and South Korea have secured a landmark deal to counter the North Korean nuclear threat.

Washington has agreed to periodically deploy US nuclear-armed submarines to South Korea and involve Seoul in its nuclear planning operations, reports BBC.

In return, South Korea has agreed to not develop its own nuclear weapons.

The Washington Declaration will strengthen the allies’ co-operation in deterring a North Korean attack, US President Joe Biden said.

Concern has been rising on both sides about the nuclear threat posed by North Korea. Pyongyang is developing tactical nuclear weapons that can target South Korea, and refining its long-range weapons that can reach the US mainland.

The US already has a treaty obligation to defend South Korea, and has previously pledged to use nuclear weapons if necessary. But some in South Korea have started to doubt that commitment and call for the country to pursue its own nuclear programme.

The South Korean President, Yoon Suk-yeol, who was at the White House for a state visit, said the Washington Declaration marked an “unprecedented” commitment by the US to enhance defence, deter attacks and protect US allies by using nuclear weapons.

The new agreement is a result of negotiations that took place over the course of several months, according to a senior administration official.

Under the new deal, the US will make its defence commitments more visible by sending a nuclear-armed submarine to South Korea for the first time in 40 years, along with other strategic assets, including nuclear-capable bombers.

The two sides will also develop a Nuclear Consultative Group to discuss nuclear planning issues.

Politicians in Seoul have long been pushing Washington to involve them more in planning for how and when to use nuclear weapons against North Korea.