South Korea’s pursuit of nuclear-powered submarines is gaining traction following U.S. President Donald Trump’s endorsement, ending decades of U.S. resistance in a move that could reshape Asia’s security landscape and escalate an underwater arms race.

Seoul has long sought to join the elite group of nations operating nuclear submarines to counter North Korea. Trump’s approval removed a key barrier by granting access to fuel under a nuclear agreement between the countries.

Still, South Korea’s rapidly developing program could irk China and pressure Japan to develop similar capabilities, analysts and former military officials say.