South Korea’s investment projects in the U.S. will remain in limbo until visa issues are resolved, the nation’s prime minister has said, urging Washington to act quickly to reassure South Koreans concerned about getting detained for working there.

"Without resolving the visa issue, meaningful progress remains virtually impossible,” South Korea’s Prime Minister Kim Min-seok said in Seoul on Wednesday in an exclusive interview that also touched on defense spending and North Korea.

"Although the projects have not been entirely halted or formally placed on hold, it will be very difficult for a large number of workers to enter or reenter the U.S. until this problem is resolved,” Kim said, referring to the visa issue, which also casts a cloud over an additional $350 billion investment fund agreed in a July trade deal.