Seoul (AFP) - North Korea fired an intercontinental ballistic missile Friday in one of its most powerful tests ever, with Japan saying the weapon may have had the range to hit the US mainland.

The missile was believed to have come down in the waters of Japan’s exclusive economic zone (EEZ), Prime Minister Fumio Kishida said as he blasted the launch as “absolutely unacceptable”.

The launch is Pyongyang’s second in two days and part of a record-breaking blitz in recent weeks, which North Korea – and some allies including Moscow – blame on the United States boosting regional security cooperation, including joint military exercises.

UN chief Antonio Guterres condemned the launch, and called on Pyongyang “to immediately desist from taking any further provocative actions,” according to his spokesperson.

The missile flew 1,000 kilometers (621 miles) at an altitude of 6,100 km, South Korea’s military said, only slightly less than the ICBM Pyongyang fired on March 24, which appeared to be the North’s most powerful such test yet.

Later on Friday, Tokyo and Washington held joint military drills in the airspace over the Sea of Japan.

“Japan Self-Defense Forces and US armed forces conducted a bilateral exercise… amid an increasingly severe security environment surrounding Japan,” a joint staff statement distributed by the Japanese defence ministry said.

“This bilateral exercise reaffirms the strong will between Japan and the United States to respond to any situation.”

US Vice President Kamala Harris convened a meeting on the sidelines of an Asia-Pacific summit in Bangkok to discuss the launch with regional leaders.

“We strongly condemn these actions and we again call for North Korea to stop further unlawful, destabilising acts,” Harris said.

Later Friday, a senior official accompanying Harris said Washington will ask China, North Korea’s primary ally, to help rein in Pyongyang.

“It will definitely be part of our diplomacy to try to get China to join the countries that are on record condemning this today,” the official said, speaking on customary condition of anonymity.

- ‘Lofted trajectory’ -

North Korea, led by Kim Jong Un, has fired scores of ballistic missiles this year – far more than any other year on record – and recent launches have been increasingly provocative, including firing a missile over Japan last month, triggering a rare air-raid warning.

On November 2, Pyongyang fired 23 missiles, including one which crossed the de facto maritime border and landed near the South’s territorial waters for the first time since the end of hostilities in the Korean War in 1953. Seoul called it “effectively a territorial invasion”.

The next day, North Korea fired an ICBM – although Seoul said it appeared to fail mid-flight.

Friday’s ICBM was launched at a “lofted trajectory”, Tokyo’s Defence Minister Yasukazu Hamada said, meaning the missile is fired up and not out, typically to avoid overflying neighbouring countries.

He said their calculations indicated the missile “could have had a range capability of 15,000 km, depending on the weight of its warhead, and if that’s the case, it means the US mainland was within its range”.

In Washington, White House national security spokesman John Kirby said Friday’s launch, although highly concerning, was not deemed “a threat to homeland.”

- ‘A clear message’ -

The launch comes a day after North Korea fired a short-range ballistic missile in what Pyongyang said was a response to Sunday’s talks between Seoul, Tokyo and Washington.

The North’s foreign minister, Choe Son Hui, had warned that Pyongyang would take “fiercer” military action if the United States followed through on plans to strengthen its “extended deterrence” commitment to regional allies.

In addition to speaking to Seoul and Tokyo’s leaders, US President Joe Biden discussed North Korea’s recent missile tests with Chinese counterpart Xi Jinping earlier this week, as fears grow that the reclusive regime will soon carry out its seventh nuclear test.

The launches are “a clear message to the US and Japan”, said Han Kwon-hee, manager of the Missile Strategy Forum, adding the launches were “part of the North’s response to recent talks”.

Pyongyang is trying to show the South and America that its “missiles can easily break through their defence systems, no matter how much the two try to improve them”, Han added.

China, Pyongyang’s main diplomatic and economic ally, joined Russia in May in vetoing a US-led bid at the UN Security Council to tighten sanctions on North Korea.

Experts say North Korea is seizing the opportunity to conduct banned missile tests, confident of escaping further UN sanctions due to Ukraine-linked gridlock at the United Nations.