North Korea launched what appeared to be a short-range missile into the sea Tuesday, the South Korean military said, as the North's envoy to the United Nations insisted it had a right to test its weapons.

The missile firing was conducted as North Korea repeated a call for the United States and its ally South Korea to stop their "hostile" policy to revive nuclear talks.

Pyongyang on Monday demanded the Biden administration to permanently scrap joint military drills with South Korea even as the North continued its recent series of weapons testing apparently aimed at applying pressure on Seoul and Washington over a slow-paced nuclear diplomacy.

During an emergency National Security Council meeting, South Korea expressed regret over what it describes as "a short-range missile launch at a time when political stability on the Korean Peninsula is very crucial." Japan's Defense Ministry said it appears to be a ballistic missile.

Shortly following the launch, the North's UN ambassador Kim Song told the UN General Assembly in New York that "nobody can deny the right to self-defense for the DPRK", the North's official name.

It is the latest in a string of mixed messages from Pyongyang, coming days after North Korean leader Kim Jong Un's powerful sister Kim Yo Jong dangled the prospect of an inter-Korean meeting. Kim is a key adviser to her brother.

"We regret the missile was launched at a time when it was very important to stabilize the situation in the Korean peninsula," South Korean defense ministry representative Boo Seung-chan told a briefing.

Pyongyang has accused Washington and Seoul of "double standards," claiming the two allies denounced its weapons development while continuing their own military exercises.

The Biden administration recently announced it had put an end to the longest war in Afghanistan after two decades, Kim said, "but the U.S. is still ignoring the reality the Korean War has not ended for more than 70 years."

Tuesday's missile test by the North is the third launch this month after the country previously tested a "strategic cruise missile" and two railway-integrated ballistic missiles.

Under UN sanctions enforced over the hermit country's weapons program, North Korea has been banned from carrying out ballistic missile tests.