North Korea fired two midrange ballistic missiles from mobile launchers into the East Sea on Wednesday in an apparent show of displeasure with the increasing pressure on it to denuclearize.

Seoul berated Pyongyang for violating U.N. Security Council resolutions that ban any launches using ballistic missile technology. The launches came just as the leaders of South Korea, the U.S. and Japan reaffirmed their opposition to Pyongyang’s possession of nuclear arms.

“The launches clearly contravened U.N. Security Council resolutions, and they are grave provocations against the Republic of Korea and the international community,” Defense Ministry spokesperson Kim Min-seok told reporters.

“The launches appeared to be carried out in protest against (the three leaders’) declaration that they would not allow the North to possess nuclear weapons, and to show off its military presence.”

The North fired one missile at 2:35 a.m. and the other 7 minutes later from Sukchon, north of Pyongyang. The projectiles, presumed to be nuclear-capable Rodong-type missiles, traveled some 650 km.

“The missiles flew at altitudes of higher than 160 km and at speeds of more than Mach 7. Given their trajectory, we judged the projectiles to be Rodong missiles,” said the spokesperson.

The communist state fired the midrange missiles for the first time in nearly five years. It launched two Rodong missiles each in 2006 and in 2009. With a range of about 1,300 km, Rodong missiles are thought to target U.S. bases in Japan. Their range also covers parts of China and Russia.

The launches coincided with the fourth anniversary of the North’s torpedo attack on the South Korean corvette Cheonan that killed 46 sailors. Pyongyang denies responsibility for the attack.

Following the North’s provocative move, Seoul strengthened its defense posture in cooperation with the U.S. It also plans to consult with the U.S. and other countries to discuss how to hold Pyongyang responsible for its violation of international resolutions.

Washington said that it was considering taking “appropriate” measures in response to Pyongyang’s missile launches.

“Coming on the heels of the DPRK (North Korea)’s March 3 and Feb. 27 Scud launches, these March 26 launches of medium-range Rodong ballistic missiles represent a troubling and provocative escalation that the U.S. takes very seriously,” said Marie Harf, deputy spokeswoman for the U.S. State Department.

The missile launches were the latest in a recent series of saber-rattling moves by Pyongyang apparently designed to protest the ongoing South Korea-U.S. military drills.

On Feb. 21, three days before the beginning of the allies’ Key Resolve command post exercise, the North fired four short-range rockets into the East Sea. On Feb. 27, the North fired off four Scud missiles with a range of 220 km.

Despite criticism for its violation of the UNSC resolutions, Pyongyang fired two additional ballistic missiles, thought to be Scud-ER missiles, an upgraded version of Scud-C missiles with a range of 500 km.

The next day, the North fired four rockets. On March 16, it fired 25 “FROG” (Free Rocket Over Ground) short-range surface-to-surface rockets. The North also fired 30 FROG rockets last Saturday and 16 FROG rockets the following day.

By Song Sang-ho (sshluck@heraldcorp.com)