A Terminal High Altitude Area Defense (THAAD) interceptor is launched during a successful intercept test, in this undated handout photo provided by the U.S. Department of Defense, Missile Defense Agency. REUTERS/U.S. Department of Defense, Missile Defense Agency/Handout via Reuters

SINGAPORE (Reuters) - Plans for the deployment of the U.S. THAAD anti-missile system in South Korea are moving forward and an announcement can be expected soon, senior U.S. officials said on Thursday.

U.S. Defense Secretary Ash Carter told reporters en route to a regional security meeting in Singapore, at which he will meet his South Korean counterpart, that recent North Korean missile tests showed the need for improved missile defenses, even though the test had been failures.

“There have been five consecutive failures there, but...most of the world continues to be concerned about North Korean missile activity,” Carter said after what U.S. and South Korean officials say was the latest failed test of a North Korean intermediate range Musudan missile on Tuesday.

“Whatever the outcome of the test, the fact remains that they are trying to make those missiles fly - that’s the critical fact,” Carter said.

Carter said deployment of the Terminal High Altitude Area Defense system would come up in his meeting on Saturday with the South Korean defense minister on the sidelines of the annual Shangri-La Dialogue in Singapore, but added: “It’s not something we need to discuss much because the plans are moving forward.”

He waved aside concerns expressed by China that deployment of the THAAD system’s radars on the Korean peninsula could upset the balance of power by reducing the strategic deterrence of the Chinese ballistic missile system.

“This is an alliance decision; a decision of the United States and the Republic of Korea, which is about protecting us both from a North Korean missile attack ...The implementation will be a series of decisions that we take together and it’s for our own protection against North Korea. Everybody should understand that.”

Another senior U.S. defense official said they were still “a lot of technical issues to get through,” but “we will have a public announcement soon.” “We are in the process of continuing our discussions on deployment and we will have an announcement when we’re ready,” he said, speaking on condition of anonymity.

The United States and South Korea began formal discussions on deploying the THAAD system in South Korea after North Korea conducted a fifth nuclear test in January and launched a rocket into space the following month as part of a program seen as a cover for intercontinental ballistic missile development.