Pyongyang conducted its sixth and most powerful nuclear test on Sunday, a day after Trump said he would meet with his advisers this week to consider pulling out of the five-year-old deal.

"North Korea's latest nuclear test underscores yet again the vital importance of the strong alliance between the United States and South Korea," the statement said. "The US-South Korea agreement, negotiated under two presidents and approved by Congress, is a central element of that alliance."

South Korea is a significant economic partner, according to the lawmakers, as well as the seventh largest export market for the U.S and a vital customer for US manufacturers, services providers, farmers, and ranchers.

"Our trade relationship can be enhanced and, because KORUS's operation has presented frustrations for some important US industries and stakeholders, we must press South Korea to improve its implementation and compliance," the statement said.  "To be effective and constructive, however, we must not withdraw from the agreement while we do so. We welcome bilateral discussions to strengthen the economic ties between South Korea and the United States." (Yonhap)