Observers warned that the US deployment of the Terminal High Altitude Area Defense (THAAD) missile defense system in South Korea could further exacerbate tensions on the Korean Peninsula and threaten the tenuous stability in Northeast Asia, as US Secretary of Defense Ashton Carter arrived in Seoul on Thursday in his first official trip to Asia.
Carter is expected to hold talks with South Korean President Park Geun-hye and his South Korean counterpart Han Min-koo on Friday on how to strengthen joint defense capabilities against North Korea, Yonhap news agency reported.
North Korea fired two surface-to-air missiles off its west coast as Carter arrived in the area, South Korea's defense ministry said on Thursday. The two short-range missiles were fired on Tuesday, following the launch of another four short-range missiles on April 3.
"It's just a reminder of how tense things are on the Korean Peninsula," Carter told reporters on Thursday at Yokota air base in Japan before departing for South Korea, adding, "If it was a welcome message to me, I'm flattered."
US military officials have said a sophisticated air defense system is needed in South Korea to counter the North's missile threat, although Washington has not made a formal proposal for deploying THAAD and it is not officially on the agenda of Carter's visit.
THAAD is a US anti-ballistic missile system designed to shoot down short and medium-range ballistic missiles in their terminal phase. Lockheed Martin claimed that the system has a track record of 100 percent mission success in flight testing.
"These are missiles launched and they reinforce the missile defense preparations we've long had on the Korean Peninsula and have here, by the way, in Japan," Carter said when asked if the latest North Korean missile launch underscores the need for THAAD deployment in South Korea, Reuters reported.
Analysts have warned that deploying THAAD in the Korean Peninsula will pose a severe threat to the vulnerable stability in Northeast Asia.
"The region already faces the threat of growing instability due to historical, territorial and maritime disputes. The situation could be further complicated by the THAAD deployment," Zheng Jiyong, director of the Center for Korean Studies under the Shanghai-based Fudan University, told the Global Times.
The move has sparked strong opposition from stakeholders in the area.
North Korea's Rodong Sinmun, a newspaper under the Workers' Party, slammed the US over the possible deployment and said it will immediately take revenge if even "a blaze of fire" hits North Korean territory.
China's Defense Minister Chang Wanquan in February expressed his concerns over the deployment in a meeting with his South Korean counterpart in Seoul.
The THAAD system will increase military pressure felt by China by monitoring Chinese air activities and threatening China's military deterrent capability, Han Xudong, a professor from People's Liberation Army National Defense University, wrote to the Global Times.
Russia's foreign ministry also said in a statement in March that deploying THAAD "could serve as another push toward an arms race in Northeast Asia and further complicate any resolution of the nuclear issues on the Korean Peninsula."
"Such a development cannot but cause concern over the destructive influence of US global missile defense on international security," the statement said.
According to Yonhap, during a visit to an airbase to the south of Seoul, Carter said the US will beef up military hardware in the Asia-Pacific region by deploying the latest stealth fighter jets, stealth bombers and warships there, as the US attached high importance to this region.
The involvement of the three powers presents a serious test of Seoul's diplomacy, which has remained silent to avoid being forced to choose sides. It adopted a policy of "three nos" regarding the missile defense system - no decision has been made, no consultation with the US is taking place and no requests have been made by Washington.
The South Korean economy is heavily dependent on China, which is its largest trading partner. It relies on the US to fend off threats to its national security.
Analysts have called Seoul's efforts to seek economic benefits from China while leaning on Washington for security unsustainable.
"South Korea is very much caught in between … A possible solution for South Korea to solve its THAAD problem is to explain its dilemma to all three powers and try to postpone deployment for as long as it can," Zheng said.
Meanwhile, South Korea and the US have been engaged in a flurry of diplomatic and military activities recently, including the Defense Trilateral Talks, which will be held in Washington DC in mid-April between the US, Japan and South Korea, and the two US-South Korean joint drills, Key Resolve, which wound up last month, and Foal Eagle, which will run until April 24.