North Korea has launched two medium-range Nodong ballistic missiles into the Sea of Japan, the latest provocation from that country that is increasing tensions on the Korean Peninsula. The launches are in violation of existing United Nations Security Resolutions barring North Korea from conducting ballistic missile tests.

"The U.S. tracked the launch of two ballistic missiles from North Korea. Both are believed to be Nodong medium range ballistic missiles," said U.S. defense official.

"Neither was assessed to be a threat to the U.S. or our regional allies," said the official. "These launches are a violation of multiple UN Security Council resolutions.

The missiles were launched early Friday morning Korea time from an eastern province of North Korea. The defense official said both missiles were fired from road-mobile transporter erector launchers.

Reports from the South Korean military indicated the missile traveled a distance of 500 miles before crashing into the Sea of Japan.

Earlier this week, the United States confirmed that the two missiles North Korea had fired last week into the Sea of Japan were also ballistic missiles.

On Wednesday President Obama ordered new U.S. sanctions against North Korea following a nuclear test in January and a long-range ballistic missile launch in February.

The medium range ballistic missile launches come as the United States and South Korean are in the middle of two annual military exercises. North Korea maintains that the exercises are preparation for an invasion of its territory, the U.S. and South Korea say the exercises are defensive in nature.

There are 28,000 U.S. military personnel stationed in South Korea.

Last week North Korea claimed that it had succeeded in miniaturizing a nuclear warhead small enough to be fitted on a ballistic missile. American officials refuted those claims.