"It appears to be a routine exercise," said US national security council spokesman Gordon Johndroe.

The State Department also said the tests would not affect ongoing international talks aimed at halting North Korea's nuclear program.

"As far as I know, it doesn't have any particular implication to the six-party talks," said State Department spokesman Tom Casey.

Pyongyang agreed at the talks in February, involving China, Japan, Russia, the two Koreas and the United States, to scrap its nuclear programs, with the shutdown of its Yongbyon reactor to be the first step.

But it made the shutdown conditional on the settlement of a dispute over accounts totalling 25 million dollars which have been frozen at the Macau-based Banco Delta Asia since 2005 under US money-laundering and counterfeiting sanctions.

US and other negotiators are struggling to settle the row over the funds which is blocking any start to the North's promised nuclear disarmament.

"This is a fairly routine test of some short range missiles," Casey said of Friday's test.

"That is something that the North Koreans have done before, so I don't think it is an issue that would appear to affect the moratorium that the North Koreans imposed on long-range missile tests some time ago."