North Korea has fired two short-range missiles a day after staging a nuclear test that caused worldwide condemnation.
North Korea launched one surface-to-air missile and one surface-to-ship missile into the sea off its east coast near the city of Hamhung.
South Korea's Yonhap news agency said each missile had a range of 130km although military officials declined to comment on what they called intelligence matters.
In a move certain to compound tensions in the region, South Korea said it would join a US-led initiative to intercept ships suspected of carrying nuclear weapons, something Pyongyang has warned it would consider a declaration of war.
The communist state yesterday staged its second underground nuclear test, with an explosive force much larger than the first in October 2006.
The nuclear test drew sharp rebuke from regional powers, and US President Barack Obama called Pyongyang's nuclear arms programme a threat to international security.
The demonstrations of military might have also taken a toll on Seoul's jittery financial markets, worried about the impact of North Korea's growing belligerence in a region which accounts for a sixth of the global economy.
Underlining concerns over how far the North might be prepared to raise the stakes, Mr Obama assured South Korean President Lee Myung-bak of Washington's unequivocal commitment to defence on the long-divided peninsula.
There is little more Washington can do to deter the ostracised North, punished for years by international sanctions and reliant on foreign aid.
The UN Security Council condemned the nuclear test and is working on a new resolution.
