President Obama says that he is "rallying the international community" to put pressure on North Korea after it attacked a South Korean island this week.

Commenting on the incident personally for the first time, Obama said that North Korea poses a "serious and ongoing threat" to the region with its aggression and nuclear ambitions.


"This is a — just one more provocative incident in a series that we've seen over the last several months, and I'm going to be talking to the president of Korea — South Korea — this evening and we'll be consulting closely with them in terms of the appropriate response," Obama told ABC News's "Barbara Walters" in an interview that will air Friday. "We strongly condemn the attack and we are rallying the international community to put pressure on North Korea." 

The president provided few hints as to what specific actions the U.S. and other nations will take against North Korea for the artillery attack, but a response appears to be already under way.

The U.S.S. George Washington aircraft carrier sailed toward the Korean peninsula Wednesday morning to participate in planned training exercises as a show of solidarity with South Korea in response to the attack on the island of Yeonpyeong. 

Obama also phoned South Korean President Lee Myung-bak on Tuesday night to express his support and say that the U.S. is "firmly and fully committed to the defense of its ally the Republic of Korea," according to the White House.

Obama would not speak further about any other planned military actions with ABC, but said that South Korea is "one of our most important allies" and "a cornerstone of U.S. security in the Pacific region."

"We want to make sure all the parties in the region recognize that this is a serious and ongoing threat that has to be dealt with," the president added.

He called on China, an important regional power, to pressure North Korea and elucidate to them "that there are a set of international rules that they need to abide by."