US President George W. Bush today said the failure of a North Korean missile test did not lessen his worries - while the UN was divided on how to respond.
As international outrage continued over Pyongyang's actions, the UN Security Council held emergency talks overnight.
Members were united in deploring North Korea's missile launches, but while Japan's UN ambassador Kenzo Oshima pushed for a swift and strongly worded resolution, Russia and China urged a more cautious approach.
Separately, the US said China should be very firm with North Korea over the missile tests, but said the shockwaves from the launches fell well short of a World War III scenario.
Mr Bush said yesterday's failure of a issile thought capable of hitting US territory did not lessen his concerns about Pyongyang's weapons programmes.
The Taepodong 2 "didn't stay up very long, it tumbled into the sea, which doesn't, frankly, diminish my desire to solve this problem", he said today in his first public remarks after North Korea fired seven missiles.
South Korea put its military on high alert and condemned the move, which it said threatened regional stability.
Japan denounced the launches as a "grave problem", put its troops and police on a higher state of alert and unleashed a package of sanctions.
White House and State Department officials stressed the seriousness of the situation, but downplayed suggestions of a full-scale global diplomatic crisis and again ruled out direct talks with Pyongyang.
"There are attempts to try to describe this almost in breathless World War III terms. This is not such a situation," said White House spokesman Tony Snow.
Secretary of State Condoleezza Rice, meanwhile, warned Pyongyang had "miscalculated" if it thought the tests would divide Washington and its Asian allies.
"There has been a very strong response to their actions. So whatever the motivations, whatever they thought they were doing, they have gotten a strong reaction from the international community."
Ms Rice did not specify what steps Washington might be considering to punish Pyongyang's actions.
But she added: "Of course the international community does have at its disposal a number of tools to make it more difficult for North Korea to engage in this kind of brinksmanship."
Washington's envoy to talks on the North Korea nuclear crisis, Christopher Hill, signalled the flavour of US diplomacy by warning in an interview with CNN International television that Beijing, host of stalled six-nation talks on North Korea, must now play a crucial role.
"We need China to be very, very firm with their neighbours and frankly with their long-term allies the North Koreans, on what is acceptable behaviour and what is not acceptable behaviour," said Mr Hill, the assistant secretary of state for East Asian and Pacific affairs.
At the UN, Japan's ambassador Kenzo Oshima said: "We hope that the response of the (security) council will be swift, strong and resolute."
US ambassador to the UN John Bolton said: "By the tenor of the statements of all of the council members, I think there is support for sending a clear signal to Pyongyang."
The international response was not limited to politicians and diplomats, with investors on both sides of the Atlantic spooked by the tests, according to analysts.
The Dow Jones Industrial Average, the Nasdaq index, Europe's main national stock markets and the DJ Euro Stoxx 50 index of leading eurozone shares all fell.
Japanese Prime Minister Junichiro Koizumi said the tests would bring no positive results for North Korea but also said it was necessary to maintain dialogue.
"We always need to leave room for dialogue. Nothing can be solved without dialogue."
Suh Choo-Suk, South Korean President Roh Moo-Hyun's security policy advisor, said: "North Korea must stop provocative activity, immediately return to six-party talks and join international efforts for nuclear non-proliferation."
South Korea also threatened to stop shipments of rice and other humanitarian aid to its neighbour, and put its military on high alert.
China, considered to exert the greatest influence on North Korea, issued a subdued reaction calling on "relevant sides" to "remain calm and exercise restraint".
"We are seriously concerned about the incident that has already happened," Beijing's foreign ministry said in a statement on its website.
The latest missile launches come during an international standoff over the Communist state's nuclear program. The North has boycotted six-party disarmament talks since November after Washington imposed financial sanctions.
Russia also condemned the tests, saying they undermined international efforts to ease nuclear tension on the Korean peninsula.
Foreign Minister Sergei Lavrov and Ms Rice discussed the matter by telephone, the government in Moscow said.
"The Russian side expressed its concern about such actions running counter to all the efforts of the international community," it said.
Mr Lavrov also spoke on the topic by telephone to Taro Aso and Ban Ki-Moon, foreign ministers of Japan and South Korea respectively.
Australia, one of the few nations to have diplomatic ties with North Korea, summoned its ambassador to protest the action and urged China to exert its influence on the rogue state.
In a first comment from North Korea, foreign ministry official Ri Pyong Dok reportedly said the launches were an issue of national sovereignty.
"We will not be restricted by any agreement regarding this issue," he told visiting Japanese journalists, Japan's Kyodo News said.