President Donald Trump threatened new trade retaliation against South Korea if it doesn't follow through on an investment in a liquefied natural gas project in Alaska, multiple outlets reported Friday, citing Trump's remarks to reporters.

"If they don't want to do it, that's OK with me - I'll just charge them more," Trump said Friday when asked about South Korea's pushback, according to the reports. He also said he didn't "jump the gun" in announcing the project.

Trump announced a $54 billion plan for the LNG export venture earlier this week as the centerpiece of Seoul's commitment to invest in the US, but the South Korean government later said it agreed only if the project proves economically viable, the reports said.

Bloomberg said it is unclear whether Trump has the power to unilaterally raise tariffs on South Korean goods after the Supreme Court curbed his tariff powers earlier this year.