North Korea early on Tuesday fired three ballistic missiles which flew between 500 and 600 kms (300 and 360 miles) into the sea off its east coast, South Korea's military said, the latest in a series of provocative moves by the isolated country.
The U.S. military said it detected launches of what it believed were two Scud missiles and one Rodong, a home-grown missile based on Soviet-era Scud technology.
According to reports by NDTV, North Korea has fired both types numerous times in recent years, an indication that unlike recent launches that were seen as efforts by the North to improve its missile capability, Tuesday's were meant as a show of force.
The launches came days after South Korea and the United States announced a final decision to deploy the Terminal High Altitude Area Defence (THAAD) anti-missile system in the South to counter threats from the North, which had prompted Pyongyang to threaten a "physical response."
"Our assessment is that it was done as a show of force," a South Korean Joint Chiefs of Staff official said at a briefing.
According to reports in Times of India, the missiles were launched from an area in the North's western region called Hwangju between 5:45 a.m. South Korea time (2045 GMT Monday) and 6:40 a.m., the South's military said, an indication that the North was confident they would not crash on its own territory.
North Korea has test-fired a series of ballistic missiles in recent months, in defiance of United Nations Security Council resolutions, including intermediate-range missiles in June and a submarine-launched missile this month.
"In addition to the basic goal of enhancing missile units' readiness to fight, it might be a way of reminding their southern neighbors that the site chosen for a THAAD battery in South Korea is within reach," Joshua Pollack, editor of the U.S.-based Nonproliferation Review, said of Tuesday's launches.
South Korea announced last week the THAAD system would be deployed in the southeastern county of Seongju.
In addition to the decision to base a THAAD system in South Korea, the United States recently angered North Korea by blacklisting its leader Kim Jong Un for human rights abuses.
"The threat to our national security is growing very quickly in a short period of time," South Korean Prime Minister Hwang Kyo-ahn told parliament on Tuesday.
Following the latest nuclear test and a February space rocket launch that was widely viewed as a missile test in disguise, the U.N. Security Council imposed tough new resolutions that further isolate North Korea.
While China supported tougher sanctions against its neighbor and ally North Korea, it has sharply criticized the decision to base a THAAD battery in South Korea, saying the move will destabilize the security balance in the region.
Japan denounced the launches.
"The latest launch is a breach of the UN Security Council resolution and is extremely hazardous to shipping and aircraft and we have strongly protested," the Japanese government said in a statement.