Following North Korea's new missile test on Sunday, speculation is growing over its type due to its unusually high flight altitude that observers say hints that the communist state is on course to develop an intercontinental ballistic missile (ICBM).

South Korea's military said the North launched the missile at around 5:27 a.m. from a site about 100 kilometers north of Pyongyang, and that it flew some 700 kilometers for half an hour before falling into the East Sea.

Japan estimated the missile's maximum altitude at over 2,000 km, an indication that the missile is a new type -- possibly with a range much longer than any other missile the reclusive state has tested so far.

It is the first time a North missile has reached such a high altitude. In June, Pyongyang was seen as having successfully launched an intermediate-range missile with a maximum flight altitude of 1,400 km.

Experts said that the missile appeared to have been fired at a steeper-than-usual angle for trial purposes, and that had it been fired at lower -- or normal -- angles of 30 or 40 degrees, it would have traveled 4,500 kilometers or farther.

"If the missile reached a maximum altitude of 2,000 km, chances are high that it is a long-range missile," Chang Young-keun, a missile expert at Korea Aerospace University, told Yonhap News Agency.

"The missile, fired Sunday, appears to be similar to the KN-08 or KN-14," he added, referring to the North's intercontinenta ballistic missiles that have yet to be tested publicly.

Kim Dong-yup, a professor at the Institute for Far East Studies at Kyungnam University, raised the possibility that the missile is likely to be an upgraded Pukguksong-2 missile that Pyongyang fired in February. He also gave the missile an estimated range of 7,000 km -- enough to target the U.S. Pacific Command (PACOM) in Hawaii.

"I personally believe that Pyongyang did not use the maximum capability of the Pukguksong-2 missile in its February experiment, and that it might have used its full capability in the latest test this morning," Kim said.

"The flight altitudes of ICBMs are usually between 1,000 and 1,500 km, but this missile reached a maximum altitude of 2,000 km meaning it could travel 6,000 to 7,000 km," the missile expert added, noting the North's missile could possibly target the Hawaii-based PACOM.

PACOM claimed that the missile flight was not "consistent" with an ICBM.

David Wright, co-director of the Global Security Program at the Union of Concerned Scientists, told the Associated Press that the missile could have a range of 4,500 km had it been flown on a "standard" trajectory.

If the North's latest missile launch is confirmed to be a success, Pyongyang is now equipped with a wide range of ballistic

 missiles that can target U.S. military installations in South Korea, Japan, Guam and potentially Hawaii, observers noted.

The North's Scud missiles with ranges of 300-500 km aim to strike South Korean targets, while its Rodong missiles with ranges of some 1,300 km can strike Japan. Its Musudan intermediate-range missiles with ranges of over 3,000 km put the U.S. strategic military base in Guam within striking range. 

Pyongyang's missiles that target Japan have been particularly worrisome, as they could pose serious obstacles to the augmentation of U.S. troops from Japan to the Korean Peninsula in case of a peninsular contingency.

The North's latest provocation is expected to accelerate Seoul's project to build a set of defense systems to counter Pyongyang's nuclear and missile threats, such as the Korea Air and Missile Defense system (KAMD) and the Kill Chain preemptive strike program. 

New South Korean President Moon Jae-in directed the military to check on the progress of the development of the KAMD and speed it up.

Regardless of its range, analysts said that the latest missile provocation underscores Pyongyang's persistent pursuit of delivery vehicles for its nuclear weapons.

Along with its land-based launch platform, the North has also been pushing for a submarine-launched ballistic missile, which is hard to detect before it emerges from the water. Along with nuclear-capable bombers and ICBMs, the SLBM completes the strategic nuclear arsenal, which experts call the "nuclear triad."

Fears about SLBMs stem from the North's potential "second-strike capability" to launch a sudden nuclear retaliation if it faces a "first strike" from enemy forces.

Second-strike capability forms the basis of a condition referred to as "mutual assured destruction" that is credited for maintaining the "long peace" between the U.S. and the Soviet Union during the Cold War. Under the condition, one dares not initiate nuclear warfare that would lead to mutual annihilation. (Yonhap)