The national security advisers of South Korea and the United States held their first phone conversation Wednesday and pledged to carry out the deployment of a US missile defense system here as planned, the presidential office said.

Kim Kwan-jin, chief of South Korea's National Security Office, and H.R. McMaster, the Trump administration's national security adviser, agreed to respond firmly to North Korea's military provocations during their talks that lasted for 30 minutes, the presidential office Cheong Wa Dae said in a press release.

"The two sides reconfirmed the need to deploy a Terminal High Altitude Area Defense battery in order to counter the North's nuclear and missile threats and agreed to push ahead with the plan without setbacks," it said.

The talks came one day after the Seoul government signed a land-swap deal with the country's retail giant Lotte Group to secure the site for the missile defense battery. (Yonhap)