June 9 (UPI) -- The decision to deploy the missile defense system THAAD in South Korea is "incredibly important" for the United States, the State Department said Thursday.
State Department spokeswoman Heather Nauert told reporters at a regular press briefing U.S. President Donald Trump met with State Secretary Rex Tillerson and Defense Secretary James Mattis on Thursday morning in the Oval Office, to discuss security on the Korean peninsula and in the Middle East.
Trump officials agreed THAAD deployment is of the highest priority, Nauert said.
"THAAD is something that's important to not only protect U.S. forces, to protect our alliance, and...help to further strengthen the region," Nauert said, declining to comment on reports of the delay in the deployment of four additional THAAD launchers.
"This is a conversation that's taken place at the highest level. We are committed to our South Korean ally. That commitment remains ironclad," she added.
The delay has irritated U.S. lawmakers, including U.S. Sen. Dick Durbin, D-Ill., who said this week he is "troubled" by the postponement following a decision by South Korean President Moon Jae-in to conduct an expanded environmental impact assessment.
Nauert also said the United States will continue to work with other countries to exert pressure on North Korea.
"This is the beginning of what will undoubtedly be a long process to get North Korea to come to the realization that its provocative actions [are] destabilizing not just for the region," the spokeswoman said.
Seoul's presidential Blue House has promised to complete THAAD deployment after the environmental assessments are conducted.
South Korea has tried to assure the public the agreement to deploy the system in coordination with the United States remains unchanged, Yonhap reported Friday.
The assessment is to ensure transparency in South Korea, the Blue House said.