North Korea fired three ballistic missiles early on Tuesday which flew between 500 and 600 kilometers (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.

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.

“This smells political rather than technical to me,” said Melissa Hanham, a senior research associate at the U.S.-based Middlebury Institute of International Studies at Monterey, California.

“I think the number and distance of the missiles lets them remind the ROK (Republic of Korea) of what they are up against,” she said, referring to South Korea by its official name.

The launches came days after South Korea and the United States announced a final decision to deploy the Terminal High Altitude Area Defense (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.

The missiles were launched from an area in the North's western region called Hwangju between 5:45 a.m. South Korea time (04:45 p.m. EDT 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.