SEOUL, April 28 (UPI) -- North Korea fired a mid-range Musudan missile early Thursday, but South Korea called the launch a "failure."
The projectile exploded and "crashed shortly after it was launched," a South Korean official said, according to CNN.
Seoul is investigating the launch, the second failure of a Musudan missile in two weeks.
North Korea also tried to fire a mid-range missile on April 15, the birthday anniversary of North Korean founder Kim Il Sung.
South Korea had stated the failure would not mean the end of provocations, and that unsuccessful attempts could actually raise the possibility North Korea could launch more missiles.
Seoul is also not ruling out the possibility of a fifth nuclear test before the May 6 Seventh Party Congress.
The Musudan is capable of reaching a range of up to 2,500 miles, Yonhap reported.
But Thursday's missile did not reach an elevation of 500 meters before it crashed into a coastal area, according to data from South Korean radar.
An unidentified South Korean military official told press the launch came too soon. The North didn't leave enough time between the last failed launch on April 15 and Thursday to take corrective measures, the official said.
The missile was launched hastily ahead of the Seventh Party Congress on May 6, experts say.
Officials also said there was likely a problem with the rocket's engine. A defect in one of the engine nozzles, connected to the fuel tank, was likely the source of the tank's explosion.
Lee Chun-geun, a researcher at South Korea's Science and Technology Policy Institute, said that problems arise in a Musudan missile when fuel becomes exposed to an oxidizing agent.
The Musudan was built on the base of a Russian R-27 missile but has been modified to fit a larger fuel tank, according to Yonhap.