White House Indo-Pacific Coordinator Kurt Campbell gave an emergency security briefing to a delegation of South Korea's ruling People Power Party in Washington after North Korea's latest long-range missile launch, lawmakers said.

On Wednesday, Pyongyang fired a Hwasong-18 solid-fuel intercontinental ballistic missile into the East Sea, the first launch in about three months, demonstrating significant progress in its pursuit of long-range nuclear missiles capable of reaching the United States.

The firing came as the People Power Party delegation, led by leader Kim Gi-hyeon, was in Washington to discuss ways to strengthen the alliance between the two countries. Campbell invited the lawmakers to the White House for a surprise briefing Wednesday.

During the 40-minute meeting, Campbell stressed that South Korea and the US should further strengthen the alliance between the two countries, as well as trilateral security cooperation with Japan, to cope with growing threats from North Korea, according to Rep. Kang Min-kuk.

Campbell was also quoted as expressing support for President Yoon Suk Yeol's call for a strong collective security posture with Japan, Australia and New Zealand. Yoon made the remark while meeting with his counterparts from the AP4 -- South Korea, Japan, Australia and New Zealand -- on the sidelines of a North Atlantic Treaty Organization summit.

The previously unscheduled briefing lasted approximately 40 minutes, following a luncheon meeting held the previous day. Reps. Kim, Kang and Lee Chul-gyu were in attendance.

Kim is leading a delegation of party members on the seven-day trip, which also includes stops in New York and Los Angeles for meetings with US government officials and congressional leaders. The delegation has departed for New York. (Yonhap)