A submarine ballistic missile is launched at an undisclosed location in North Korea on April 23, 2016 (Photos by AFP)
North Korea has fired a submarine–launched ballistic missile, just two days after threatening a nuclear attack in retaliation to large-scale US and South Korean joint military exercises.
According to a statement released by South Korea's Joint Chiefs of Staff, the missile was launched off the North’s east coast in the Sea of Japan late on Tuesday.
Japanese Prime Minister Shinzo Abe said that Tokyo "strongly protested" the launch, which he referred to as a "grave threat" to his country.
He added that Japan’s self-defense force would remain on alert in case of further launches by Pyongyang.
Earlier, Pyongyang has warned that the massive joint military exercises being held by the US and the South are pushing the situation on the Korean peninsula "to the brink of a war" and called for an urgent meeting of the UN Security Council.
In a letter sent to the council, North Korea's UN Ambassador Jan Song Nam accused Washington of "creating the danger of war" with the drills.

A South Korean soldier wearing a gas mask stands guard during an anti-terror drill on the sidelines of South Korea-US joint military exercise, called Ulchi Freedom, at a subway station in Seoul on August 23, 2016.
The Korean People's Army (KPA) issued a statement Monday morning, threatening a “preemptive retaliatory strike,” should the war drills threaten Pyongyang’s sovereignty.
The annual two-week “Ulchi Freedom Guardian” maneuver, which is largely computer-simulated, started on Monday with the participation of 50,000 Korean and 30,000 US soldiers.
Meanwhile, Japan has called on the North to refrain from carrying out provocations, such as further missile tests in the region.  
"Japan strongly urges North Korea to refrain from further provocations and to comply faithfully and fully with the relevant Security Council resolutions," said Kiyoshi Odawara, Japan's parliamentary vice-minister for foreign affairs.
North Korea said in January it had successfully detonated a hydrogen bomb, its fourth nuclear test, and vowed to build up its nuclear program as deterrence against potential aggression from the US and its regional allies.

This undated file photo released by North Korea's official Korean Central News Agency (KCNA) on July 21, 2016 shows a missile fired during a drill by Hwasong artillery units of the Strategic Force of the Korean People's Army. 
A month later, Pyongyang launched a long-range rocket which it said placed an earth observation satellite into orbit. Washington and Seoul denounced it as a cover for an intercontinental ballistic missile test.
North Korea says it will not abandon its nuclear “deterrence” unless Washington ends its hostile policy toward Pyongyang and dissolves the US-led command in South Korea. Thousands of US soldiers are stationed in South Korea and Japan.