North Korea launched three short-range missiles that could be used to carry a nuclear bomb. This is the country's second test in about seven weeks.
"These actions, while not a surprise given its statements and actions to date, are a matter of grave concern to all nations," Obama said. "North Korea's attempts to develop nuclear weapons, as well as its ballistic missile program, constitute a threat to international peace and security."
North Korea tested a long-range missile on April 5 that the U.S. said at the time was a failure.
As the Wall Street Journal reports, though, Obama and other nations appear to be taking this recent test more seriously.
"The danger posed by North Korea's threatening activities warrants action by the international community," Obama said. "We have been and will continue working with our allies and partners in the Six-Party Talks as well as other members of the U.N. Security Council in the days ahead."
The U.N. Security Council has scheduled an emergency meeting Monday afternoon.
"By acting in blatant defiance of the United Nations Security Council, North Korea is directly and recklessly challenging the international community," Obama said. "It will not find international acceptance unless it abandons its pursuit of weapons of mass destruction and their means of delivery."