Continued from page 1

For this reason, many specialists think Pyongyang is building a nuclear missile-based deterrent. This is tacit recognition that its conventional military is no match for the South Korea-U.S. alliance.

“North Korea is the weakest state in the region,” said Dan Pinkston, who heads the International Crisis Group’s Seoul office. “They don’t have the technological or economic base to compete conventionally, so they have to rely on asymmetric capabilities.” In a possible indication of the North’s lack of conventional strength, no clashes took place in June in the Yellow Sea despite numerous predictions that North Korea would launch naval provocations there following its recent missile and nuclear tests.

Yonhap, citing an unnamed military official, reported that all four missiles fired Thursday flew about 60 miles and identified them as KN-01 missiles with a range of up to 100 miles.

President Obama told the Associated Press in an interview Thursday that he was trying to “keep a door open” for North Korea to return to international nuclear disarmament talks, but the country must abandon its nuclear weapons programs before it can join the world community.

He expressed optimism that he could get international agreement for even tougher action if North Korea does not heed warnings to pull back.

“In international diplomacy, people tend to want to go in stages,” Mr. Obama said. “There potentially is room for more later.”

White House press secretary Robert Gibbs told reporters later that the Obama administration was not surprised by the missile test, saying that it was probably not the last challenge the North Koreans would pose the international community.

“The North Koreans said they were going to launch these missiles. I don’t think it’s surprising that they’ve launched these missiles,” Mr. Gibbs said. “I take the North Koreans at their word that they’re going to continue their provocative actions.”

Christina Bellantoni in Washington contributed to this report.