South Korea is going through an "identify crisis" again over its security dependence on the United States, especially following North Korea's two deadly attacks in 2010, an alliance politics expert said Wednesday.

"I think it's fair to say there is an identify crisis in South Korea," William Tow, professor at Australian National University (ANU), said at a roundtable in Washington. "The identity crisis there is essentially about, 'Can we keep the Americans involved?'"

Tow, acting head of the Department of International Relations at ANU's School of International, Political and Strategic Studies, was briefing the results of the university's three-year project to study bilateral and multilateral security structures in the Asia-Pacific region.

A formal report will be published in the coming months, he said.

The scholar said South Korea's identify crisis has become evident particularly after the sinking of the Cheonan naval ship and the shelling of a border island that killed a total of 50 sailors and civilians.

He said his study team made a trip to South Korea two weeks ago, during which there was "very little talk about unification."

"A lot more talk about how South Korea is going to be able to continue with the United States to defend itself apart from moving toward some type of nuclear posture," he said.

He was referring to a demand by some people in the South that it should develop its own nuclear weapons capability to counter the North's threats.

Tow said, however, many South Koreans appear not to be "thrilled" by the idea.

Under the liberal administration of the late President Roh Moo-hyun, South Korea engaged in internal debates over its dependence on Washington. The Roh government sought a "balanced role" between the U.S. and China.

Tow said Japan is also undergoing an identify crisis that is different from that of South Korea as it is developing how Tokyo should behave in a foreign policy sense.

On the U.S.-led multilateral alliance, he said it seems to be shifting from "threat-centric" to "order-centric" after the demise of the Soviet Union and the end of the Cold War.

The theory that an alliance dissolves if a common threat disappears has "been turned on its head" over the last 10-15 years, he pointed out.

The U.S. bilateral and multilateral alliance system has not only survived but also thrived as shown in NATO, he added. (Yonhap News)