At the talks, US President Joe Biden reaffirmed a commitment to reinforce extended deterrence and defend the two Asian allies with a "full range of capabilities", including nuclear weapons.

Choe said the three countries' "war drills for aggression" failed to rein in the North but would rather bring a "more serious, realistic and inevitable threat" upon themselves.

"The keener the US is on the 'bolstered offer of extended deterrence' to its allies and the more they intensify provocative and bluffing military activities ... the fiercer the DPRK's military counteraction will be," Choe said in a statement carried by the official KCNA news agency.

She referred to her country by the initials of its official name, the Democratic People's Republic of Korea.

"The US will be well aware that it is gambling, for which it will certainly regret," Choe added.

The South Korean and US militaries carried out missile defence drills after the North's latest launch, Seoul's Joint Chiefs of Staff said, strongly condemning it.

"We urge an immediate halt of North Korea's series of ballistic missile launches, which is a grave provocation damaging peace and stability," the joint chiefs said in a statement.

The United States has said since May that North Korea is preparing to conduct its first nuclear test since 2017, but its timing remains unclear.

Washington, Seoul and Tokyo said in a joint statement after the summit that Pyongyang's nuclear testing would incur a "strong and resolute response."

Choe said the North's military activities are "legitimate and just counteractions" to the US-led drills.

South Korea's Unification Minister Kwon Young-se, who handles intra-Korea affairs, said the North might postpone its nuclear test for some time, citing China's domestic political schedule.

"North Korea has also achieved some political effects by codifying its nuclear law in August, so it might not have immediate needs for a nuclear test," Kwon said in an interview with Yonhap news agency released on Thursday.