North Korea fired off four short-range ballistic missiles into the Yellow Sea on Saturday, Seoul said, as the U.S. deployed two B-1B bombers for joint military drills with South Korea.

The South Korean military said it had detected the launches from the Tongrim county area in the country’s northwest, near its border with China, between around 11:32 a.m. and 11:59 a.m., the Yonhap news agency reported.

The missiles flew about 130 kilometers, hitting a maximum altitude of 20 km with a top speed of Mach 5.

Saturday’s missiles were the latest in a flurry of more than 30 launches by the North since Wednesday, including one of an intercontinental ballistic missile that was believed to have failed in-flight over the Sea of Japan. The launch was initially believed to be headed over Japan, triggering a rare warning by the country’s J-Alert emergency broadcasting system that urged people to take shelter.

That launch came after the United States and South Korea on Monday kicked off the large-scale Vigilant Storm joint air exercises, which have featured about 240 warplanes — including advanced F-35 stealth fighters — conducting around 1,600 sorties.

The exercises had initially been scheduled to wrap up Friday, but were extended one day, allowing for the U.S. B-1Bs to join four U.S. F-16 fighters and four South Korean F-35A fighters on Saturday.

The dispatch of the U.S. bombers from the island territory of Guam also saw them link up for joint “tactical exercises” with Air Self-Defense Force F-2 fighter jets northwest of Kyushu.

The deployment of the U.S. strategic bombers, which are not nuclear-capable but can fire cruise missiles and laser-guided bombs, was the first since 2017, when tensions between Washington and Pyongyang had hit a fever pitch. Saturday's move was widely seen as a show of force by the allies, as North Korea’s spate of missile launches continue unabated.

The decision to send the B-1Bs, which North Korea has claimed are capable of carrying nuclear bombs, was expected to be seen as especially provocative by the regime in Pyongyang. The supersonic bombers have reportedly been the centerpiece of plans for pre-emptive strikes by the United States on North Korean missile sites — and potentially the country’s leadership.

A news broadcast with file footage of a North Korean missile launch at a railway station in Seoul on Wednesday. | AFP-JIJI
A news broadcast with file footage of a North Korean missile launch at a railway station in Seoul on Wednesday. | AFP-JIJI

South Korea’s spy agency has in the past said the North has also failed to detect the bombers during shows of force in airspace over international waters.

On Friday, South Korea scrambled 80 of its fighter jets after detecting an unusually large contingent of around 180 North Korean warplanes mobilized in Pyongyang's airspace.

Pyongyang has lambasted this week’s joint U.S.-South Korean exercises as a rehearsal for invasion and threatened to unleash “powerful measures” if they are not halted.

This has led some observers to conclude that North Korea could be laying the groundwork for conducting its seventh nuclear test and first since 2017. South Korea, the U.S. and Japan have all said that Pyongyang has completed preparations for a blast. A green light by leader Kim Jong Un could even come sometime before the U.S. midterm congressional elections on Tuesday.

The U.S., South Korea and Japan have pledged a strong coordinated response if the North conducts a nuclear test, a move that is banned under United Nations sanctions.

Meanwhile, at least one aim of the repeated missile tests — and possible nuclear blast — could be to return North Korea to the headlines, pushing it up the White House’s agenda while at the same time normalizing its status as a nuclear power.

“The Kim regime may relish international anxiety in the lead up to its next nuclear detonation, believing that greater global attention will hasten begrudging acceptance of North Korea as a nuclear weapons state,” said Leif-Eric Easley, a professor at Ewha University in Seoul.