North Korea fires two ballistic missiles, Seoul says

North Korea fired two short-range ballistic missiles Tuesday, Seoul said, Pyongyang's second launch in three days and the first since South Korea and the United States began their largest joint military drills in five years.

Washington and Seoul have ramped up defence cooperation in the face of growing military and nuclear threats from the North, which has conducted a series of increasingly provocative banned weapons tests in recent months.

South Korea's Joint Chiefs of Staff said the military had "detected two short-range ballistic missiles" fired between 7:41 am (2241 GMT) and 7:51 am, which flew some 620 kilometers.

"Our military has strengthened surveillance and vigilance in preparation for additional launches," it added.

Japanese government spokesman Hirokazu Matsuno said the missiles had not landed in his country's waters, though Tokyo suspected North Korea might take "further provocative action."

The launch comes just days after Pyongyang fired two "strategic cruise missiles" from a submarine in apparent protest over the US-South Korea exercises.

Known as Freedom Shield, the drills started Monday and will run for 10 days.

In a rare move, Seoul's military this month revealed the two allies' special forces were staging military exercises dubbed "Teak Knife" -- which involve simulating precision strikes on key facilities in North Korea -- ahead of Freedom Shield.

The Freedom Shield exercises focus on the "changing security environment" due to North Korea's redoubled aggression, the allies have said.

They will "involve wartime procedures to repel potential North Korean attacks and conduct a stabilisation campaign in the North", the South Korean military said previously.

It emphasised that the...