US Vice President Joe Biden on Monday embarked on a three-nation Asia tour amid heightened tensions over China's recent declaration of a new air defence zone in the East China Sea.
Biden is to visit Japan and China from Monday through Thursday to discuss the escalating controversy and other bilateral issues. He is to arrive in Korea on Thursday to coordinate responses to China's unilateral air demarcation.
Seoul is leaning toward expanding its air defence zone, a move which analysts say Washington might not welcome given that Seoul's expansion of its zone could weaken the firm US rationale against Beijing's unilateral move to alter the status quo.
Seoul is considering expanding its Air Defence Identification Zone to include airspace over Ieodo, a submerged rock in the East China Sea; the country's southernmost island of Marado; and Hongdo, an inhabited island south of Geojeodo.
Set up by the US Air Force to block communist forces during the Korean War in 1951, South Korea's zone does not cover the airspace over some remote spots, including Ieodo, that lie in the overlapping exclusive economic zones of Korea and China.
After China unilaterally incorporated the area over Ieodo in its new air zone, South Korea has made a botched call for adjustment and sought to include the rock in its own zone.
Earlier last week, President Park Geun-hye directed her security staff to weigh the expansion amid public anxiety over China's increasing assertiveness, which has also unnerved other regional stakeholders such as the US and Japan.
The Seoul government will finalize its decision after it holds a policy coordination meeting with the ruling Saenuri Party. The meeting, which was initially planned for Tuesday, was deferred after the government said it needed more time for internal discussion.
Unlike Beijing, Seoul plans to consult with the US, China and Japan over its desire to expand its air zone, officials said.
Washington has criticised Beijing's unilateral territorial assertions in both the East and South China Seas. It views the assertions as an attempt at altering the regional status quo in favour of its national interests, while Beijing argues it is seeking to secure its territorial integrity.
Experts differ over Seoul's move toward the expansion of its air zone.
Some argue that Seoul's expanded air zone would not be recognised by any of the regional powers, and that the expansion would only deepen territorial animosities and destabilize the security landscape.
Others claim that Seoul should resolutely respond to any attempt at encroaching upon its territory.
Last week, Seoul demanded Beijing adjust its new air defence rules. Beijing rejected this. On Sunday, top security officials gathered at Cheong Wa Dae to discuss ways to protect the country's national interests, including the expansion of its air defence zone, in accordance with international law.