North Korea fired two short-range ballistic missiles into the sea on Thursday, hours after US Vice President Kamala Harris flew home from a visit to South Korea during which she emphasised the “ironclad” US commitment to the security of its Asian allies.

It was the third round of missile launches by North Korea this week, extending a record pace in weapons testing as the country accelerates a push to expand its arsenal and pressure Washington to accept it as a nuclear power.

“South Korean military detected two short-range ballistic missiles fired from Sunchon, South Pyongan province, toward the east coast between 8:48pm [11:48 GMT] and 8:57pm [11:57 GMT] … Amid strengthened surveillance and vigilance, our military maintains full preparedness while working closely with the US,” said the United States Joint Chiefs of Staff.

Japan’s military said it also detected a launch. North Korea fired two short-range ballistic missiles on Wednesday, while Harris was in Japan, and fired one before she left Washington on Sunday.

Public broadcaster NHK said the projectile “appears to have fallen outside Japan’s Exclusive Economic Zone”, citing unnamed sources from the defence ministry.

Harris earlier capped her four-day trip to Asia with a meeting with South Korean President Yoon Suk-yeol and a stop at the Demilitarised Zone (DMZ) dividing the Korean Peninsula, where she addressed the threat posed by the increasingly hostile North.

Speaking at the DMZ, Harris said the US commitment to South Korea’s defence was “ironclad”, adding that the allies were “aligned” in their response to the growing threat posed by the North’s weapons programmes.

Washington has about 28,500 troops stationed in South Korea to help protect it from North Korea, and the allies are conducting a large-scale joint naval exercise this week in a show of force.

At the DMZ, Harris went to the top of a ridge, near guard towers and security cameras. She looked through bulky binoculars as a South Korean officer pointed out military installations on the southern side.

Then a US officer pointed out some of the defences along the military demarcation line, including barbed-wire fences and claymore mines. He said American soldiers regularly walk patrols along a path.

“It’s so close,” Harris said.

Harris then visited one of a row of blue buildings that straddle the demarcation line, where an American officer explained how the buildings are still used to conduct negotiations with North Korea. Sometimes they pass messages back and forth and sometimes they use a megaphone, he said.

“That’s high tech,” Harris joked, before adding, “We’ve stepped into history.”

“It’s still going,” the colonel said.

Harris agreed. “The past and present are happening every day.”

She then walked out of the building and up to the demarcation line. On the North Korean side, two figures dressed in what appeared to be hazmat suits peeked out from behind a curtain in a second-floor window. Then they disappeared back inside.

Harris described the North Korean missile launches as provocations meant to “destabilise the region” and said the US and South Korea remain committed to the “complete denuclearisation” of the North.

“In the South, we see a thriving democracy. In the North, we see a brutal dictatorship,” she said before flying out of the border on a US military helicopter.

Al Jazeera’s Rob McBride, reporting from Paju in South Korea, said the last significant visit to the DMZ was in 2019, when former US President Donald Trump met with North Korean leader Kim Jong Un.

“Hopes of North Korea giving up its nuclear weapons have all but evaporated, with leader Kim Jong Un recently enshrining in law its status as a nuclear armed power – and South Korea intelligence officials believe the North has now completed preparations for another nuclear test,” McBride said.

“It would be the first such test in five years, and comes as a US naval strike group … conducts joint drills in Korean waters – again, another first in five years.”

Seoul announced Thursday that it would hold trilateral anti-submarine drills with Japan and the US.

South Korean lawmakers briefed by the country’s spy agency said on Wednesday that the North has completed preparations for a nuclear test and a possible window for carrying it out could come between October 16 and November 7. (Al Jazeera)

•PHOTO:United States Vice President Kamala Harris uses binoculars at the military observation post as she visits the demilitarised zone separating the two Koreas, in Panmunjom, South Korea [Leah Millis/Reuters]

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