A top U.S. official says it appears North Korea has launched a short-range missile into the Sea of Japan.
"It appears that there was a test of a short-range missile by the North Koreans, and it landed in the Sea of Japan," he said.
Mr. Card made clear the Bush administration is monitoring the situation closely, and said North Korea has taken similar action in the past.
"We are not surprised by this," he said. "The North Koreans have tested their missiles before."
Earlier, on the Fox New Sunday television program, the White House chief of staff said Washington is aware of North Korea's intentions.
"Well, I think, they are looking to kind of be bullies in the world," said Mr. Card. "And they are causing others to stand up and take notice."
Mr. Card stressed that the United States remains committed to multi-national diplomacy to deal with Pyongyang's nuclear ambitions. Echoing comments made by President Bush at a news conference Thursday, he said North Korean leader Kim Jong Il has not kept his word, and the United States has no confidence that he ever will.
"We have the Russians and the Chinese and the South Koreans and the Japanese working very closely with us to try to have them [North Koreans] recognize that, first of all, they [North Koreans] have to keep their word," he added. "Second of all, they must not have any program that could lead to nuclear weapons."
Appearing on CNN, Senator Carl Levin, the top Democrat on the Senate Armed Services Committee, said multi-party negotiations are important. But he stressed, they are not enough.
"We also ought to do what our ally, the South Koreans, want us to do, which is also, in addition to the multi-lateral talks, talk directly to the North Koreans," he said. "That is what has been missing."
North Korea walked away from the six-nation negotiations in February.