SEOUL, South Korea — North Korea test-fired five short-range missiles into the sea off its east coast Sunday, raising cross-border tensions ahead of Seoul's planned joint army drills with the US.

The North fired the missiles into the East Sea (Sea of Japan) from its eastern city of Wonsan between 4:20-5:10 pm, (0720-0810 GMT) Seoul's defence ministry spokesman told AFP.

They flew about 200 kilometers (124 miles) before landing.

"We are closely watching for any signs of additional missile launches by the North," said the spokesman.

On Saturday, the North said it had test-fired an "ultra-precision" anti-ship rocket, which will be deployed across its navy "before long."

The missile tests come as South Korea and the United States prepare to start major annual joint military exercises hated by Pyongyang.

The large-scale Key Resolve and Foal Eagle exercises, which will begin in early March, look set to trigger a sharp rise in military tensions on the divided peninsula.

The Seoul and Washington also started last week a joint naval exercise involving a US nuclear submarine.

Pyongyang sees all joint US-South Korea army exercises as provocative rehearsals for invasion and has frequently demanded they be stopped.

The nuclear-armed communist country has pushed ahead with the development of ballistic missiles and rockets, despite tough sanctions imposed by the international community.

In 2012, Pyongyang demonstrated its rocket capabilities by sending a satellite into orbit, but it has yet to conduct a test that proves it has mastered the technology required for an effective inter-continental ballistic missile (ICBM) that could reach the US mainland.

Seoul's military said in January that the North had also made "significant" steps in developing technology that would allow it to mount nuclear bombs on a missile.

Pyongyang has staged three nuclear tests, most recently in February 2013 — the first since young ruler Kim Jong-Un came to power and its most powerful to date.

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