North Korea fired two short-range missiles off its east coast on Thursday, the South Korean military said, less than an hour after Pyongyang warned of an “inevitable” response to military drills staged earlier in the day by South Korean and U.S. troops.

The latest action by North Korea came as U.S. President Joe Biden’s national security adviser, Jake Sullivan, was in Tokyo for meetings with his Japanese and South Korean counterparts.

In a meeting with South Korea’s national security adviser, Cho Tae-yong, and Japan’s National Security Advisor Takeo Akiba on Thursday, the three discussed North Korea’s missile programme and confirmed that they would work closely together to get Pyongyang to abandon its nuclear weapons, according to a readout of the meeting released by Japan.

Japan’s defence ministry said the two ballistic missiles landed within its exclusive economic zone (EEZ), possibly having flown in an irregular trajectory.

The two missiles landed in the Sea of Japan about 250 km north-northwest of Hegura island, part of Ishikawa prefecture, Japan said. It was the 13th time that North Korea’s missiles landed within Japan’s EEZ, Japanese vice minister of defence Kimi Onoda said.

Japanese Prime Minister Fumio Kishida condemned the launches.

“The latest missile launch is a violation of Security Council resolutions and an escalation of provocations against the international community as a whole. We lodged a strong protest against North Korea,” he told reporters.

The government was due to hold a National Security Council meeting, Kyodo news reported separately.

Representatives for the White House and the U.S. State Department did not immediately respond to a request for comment on the launch

South Korean President Yoon Suk Yeol watched as several thousand South Korean and U.S. troops took part in joint live-fire exercises on Thursday, in the latest show of force that the allies say is necessary to deter North Korea.

A spokesperson for North Korea’s Ministry of National Defence said the drills were escalating the military tension in the region and its forces would sternly respond to “any kind of protests or provocations by enemies”.

Pyongyang unsuccessfully tried to launch a spy satellite late last month, in its first satellite launch since 2016, with the rocket booster and payload plunging into the sea.

North Korea’s ballistic missile and nuclear weapons programmes are banned by United Nations Security Council resolutions that have sanctioned the country.

Diplomatic efforts to reduce tensions or persuade Pyongyang to abandon its nuclear arsenal have been stalled.

South Korea sued North Korea on Wednesday for $35 million in compensation for a liaison office that North Korea blew up in 2020, in a case highlighting the breakdown of ties between the neighbours as the North presses on with its weapons programmes.