Trump said the United States would share technology that would allow South Korea to build a nuclear-powered submarine

GYONJU, South Korea (AP) — The United States will closely share technology it has to allow South Korea to build a nuclear-powered submarine, U.S. President Donald Trump said on social media Thursday after meeting with the country’s president.

President Lee Jae-myung assured Trump in their meeting on Wednesday that the goal was to modernize the alliance with the United States, pointing to plans to increase military spending to ease the financial burden on America.

Read more: North Korea promotes missile tests as Trump visits South Korea

The South Korean leader said there may have been a misunderstanding when they last talked in August about nuclear-powered submarines, saying his government was looking for nuclear fuel rather than weapons.

If South Korea is equipped with nuclear-powered submarines, it could help US activities in the region, Lee said.

Trump said in a separate post that the country will build its nuclear-powered submarine at the Philly shipyard, which South Korea’s Hanwha Group bought last year.

It was not clear the size or cost of the subproject, but South Korea said in talks with Trump that it had pledged $150 billion to invest in US shipbuilding capacity.

US nuclear submarine technology is widely considered some of the most sensitive technology the military possesses. The United States has been incredibly protective of that knowledge, and even the recently announced agreement with close allies the United Kingdom and Australia to help the latter acquire nuclear submarine technology does not include the United States transferring its knowledge directly.

Trump’s social media post comes ahead of his meeting with Chinese President Xi Jinping, whose country has nuclear submarines, and after North Korea in March revealed for the first time a nuclear-powered submarine under construction. It is a weapons system that could pose a major security threat to South Korea and the United States

While Trump visited South Korea, North Korea said on Wednesday that it had successfully tested cruise missiles, in the latest display of its growing military capabilities.

Pentagon officials did not immediately respond to questions about Trump’s announcement about sharing subnuclear technology with South Korea.

Bock reported from Tokyo. Associated Press writer Konstantin Torobin contributed to this report from Washington.