North Korea on Sunday fired a total of 18 short-range missiles into the Sea of Japan from its eastern coast, the South Korean Joint Chiefs of Staff announced.

The missile tests are considered to be a protest over the military maneuvers being conducted by South Korea and the United States in the southern part of the Korean Peninsula through April 18, which Pyongyang says are a practice run for invading its territory.

Initially, 10 missiles were launched about 6:20 p.m. (1020 GMT) and another eight missiles were fired off about 8:30 p.m. (1230 GMT on Monday).

"The rockets were fired in the eastern direction from the eastern coastal region (of North Korea) near Wonsan," some 150 kilometers - or 93 miles - east of Pyongyang, the South Korean Joint Chiefs of Staff said in a communique, adding that "the maximum range for these missiles is estimated to be 70 kilometers (43 miles)."

It is believed that the missiles are Soviet-designed FROG rockets, the designation being NATO's acronym for a series of short-range missiles which have been used by the North Korean army since the 1960s.

"We urge North Korea to cease new provocative actions," said South Korea's top military brass in the statement, adding that the South Korean armed forces had increased their vigilance in the face of the possibility of new missile launches.

This is the fourth test of its kind by the North Korean regime over the past three weeks, all of them apparently in response to the joint South Korean-U.S. military exercises.

The exercises, dubbed Foal Eagle, involve some 7,500 of the 28,500 U.S. troops stationed in South Korea as a deterrent to a possible invasion by North Korea. EFE