Oct. 1 (UPI) -- North Korea fired what was believed to be a submarine-launched ballistic missile from waters off its east coast on Wednesday, South Korea's military said, demonstrating its nuclear delivery capabilities just days before resuming denuclearization talks with the United States.
The missile, believed to be a type of Pukkuksong, a North Korean SLBM, was fired from off the east coast near Wonsan in an easterly direction at 7:11 a.m. and flew around 280 miles at a maximum altitude of about 565 miles, according to the Joint Chiefs of Staff.
The high altitude means the missile was fired at a high angle, and if it had been fired at a normal angle, it would have flown a much longer distance.
"Our military is monitoring the situation in case of additional launches and maintaining a readiness posture," the JCS said, calling on the North to stop such acts that heighten tensions on the Korean Peninsula.
South Korea's presidential National Security Council convened an emergency meeting and expressed strong concern over the launch.
U.S. Forces Korea said it is aware of the launch.
"We are aware of reports of a possible North Korean missile launch. We are continuing to monitor the situation and consulting closely with our allies in the region," USFK spokesperson Col. Lee Peters said in a statement sent to Yonhap News Agency.
If confirmed, Wednesday's launch will mark the North's first SLBM test since August 2016, when it test-fired a Pukguksong-1 ballistic missile off the east coast, which flew about 310 miles. So far this year, the North carried out missile and rocket launches 10 times, but all involved short-range projectiles.
The communist country then tested Pukguksong-2 missiles in 2017 after remodeling the original version into a ground-based one. The maximum flight range of both types was known to be around 807 miles, according to the defense ministry.
Along with its intercontinental ballistic missiles, the North's SLBM program is considered one of the biggest threats to the United States and its allies, as it could extend the range of the North's nuclear missiles and such a missile is hard to detect in advance before it emerges from the water.
It is not immediately known from which platform the missile was fired, though experts said it could be launched from a barge or its newly built submarine.
In July, North Korean leader Kim Jong Un inspected the new submarine, calling for the development of naval armed forces to boost the country's military capabilities, according to the North's Korean Central News Agency. The communist country was known to have built a new submarine at its naval base in Sinpo on its east coast.
Intelligence authorities in South Korea said at the time that the newly constructed submarine is ready to be deployed "soon" and seems to be capable of carrying three SLBMs.
The firing came a day after the North's First Vice Foreign Minister Choe Son Hui said that Pyongyang and Washington agreed to resume working-level nuclear talks this week. The two sides will have "preliminary contact" on Friday and working-level negotiations the following day, Choe said without disclosing the venue.
The U.S. State Department only said the two sides plan to "meet within the next week."
The nuclear talks have been stalled since the breakdown of the summit between U.S. President Donald Trump and Kim in Hanoi, Vietnam in February.
"[North Korea] appears to aim to strengthen its negotiating hand to the maximum," Defense Minister Jeong Kyeong-doo said Wednesday during an annual parliamentary audit.
"It also appears to take into consideration multiple factors, including our military's demonstration of its latest military assets yesterday," he added.
On Tuesday, South Korea officially marked its introduction of F-35A stealth fighters for the first time during the Armed Forces Day ceremony. South Korea has so far brought in eight F-35As, beginning with two in late March, under a plan to deploy 40 fifth-generation jets through 2021.
North Korea has intensified its criticism against South Korea for the introduction of such advanced weaponry, claiming that such a military buildup is aimed at destroying North Korea, and it is in violation of last year's inter-Korean military agreement that calls for halting hostility against each other.
Following Wednesday's launch, South Korea asked Japan to share related military information under the framework of the bilateral intelligence-sharing pact, according to Seoul's defense ministry.
In August, South Korea announced its decision to terminate the pact, the General Security of Military Information Agreement, after Japan extended its export restrictions on Seoul. The agreement is set to expire in November.
Japan's Chief Cabinet Secretary Yoshihide Suga told a press conference earlier in the day that North Korea launched two ballistic missiles and that one of them fell into the country's exclusive economic zone.
After an 18-month hiatus, North Korea resumed its weapons tests in May. The last one took place on Sept. 10 when it is believed to have test-fired two or three projectiles from what it dubbed its "super-large" multiple rocket launcher system.
During the previous 10 rounds of tests, North Korea was believed to have showed off four new types of weapons: its version of Russia's Iskander ballistic missile, its version of the U.S.' Army Tactical Missile System, "a new large-caliber multiple launch guided rocket system" presumed to be a 400mm one and the super-large launcher.
Under U.N. Security Council resolutions, the North is banned from test-firing ballistic missiles.
But Trump has brushed off recent tests by the North and boasted of his good relations with Kim, stressing that Pyongyang has not tested long-range missiles or nuclear devices in the current phase of peace efforts.