President Donald Trump threatened Friday to double tariffs on South Korean imports if the country backs out of its planned investment in the Alaska liquefied natural gas pipeline.

Trump made the remarks to reporters at the White House as he departed for a campaign event. He defended his earlier announcement and stated that if South Korea does not sign the deal soon, he will "double it up."

The comments follow Trump's September 30 announcement that South Korea had agreed to invest up to $200 billion in U.S. projects. This package included approximately $54 billion toward the Alaska LNG pipeline, along with funding for eight nuclear power plants and a major natural gas facility in Texas.

The investments stem from a 2025 trade agreement in which South Korea pledged $350 billion in U.S. investments in exchange for reduced tariffs on its exports, lowered from 25 percent to 15 percent.

South Korean officials quickly clarified after the September 30 event that no final decision had been reached on the Alaska project. They described it as under review for commercial viability and legal compliance.

Trump's threat underscores his administration's focus on enforcing trade deals to advance American energy production and infrastructure. The Alaska LNG pipeline would transport natural gas from the North Slope to southern ports for export, supporting long-term U.S. energy dominance.

The project has drawn support from Alaska Republicans, including Sen. Dan Sullivan, who faces a competitive reelection race. The pipeline spans more than 800 miles and targets Asian export markets.

Tariff enforcement remains a central tool in the administration's approach to bilateral trade, with officials signaling that non-compliance could reverse recent reductions.