SEOUL (AP): North Korea fired two short-range ballistic missiles off its eastern coast on Monday in its second weapons test in three days that drew quick condemnation from its rivals.

The weapons firings follow an intercontinental ballistic missile (ICBM) launch on Saturday and North Korea's threats to take an unprecedented strong response to U.S.-South Korean military drills that the North views as an invasion rehearsal. Some experts say North Korea could use a new testing spree to expand its arsenal and intends eventually to use its boosted capability as leverage in negotiations with the United States.

South Korea's military said it detected the two missile launches from a western coastal town, just north of Pyongyang, the North Korean capital, on Monday morning. Japan said both missiles landed in the waters between the Korean Peninsula and Japan and that no damage involving aircraft and vessels in the area was reported. According to Japanese and South Korean assessments, the North Korean missiles flew at a maximum altitude of 50-100 kilometres (30-60 miles) and a distance of 340-400 kilometres (210-250 miles).

South Korea's military said North Korea's repeated missile launches are "a grave provocation" that undermines international peace. Japan condemned the launches as a threat to the peace and safety of Japan and international society.

The U.S. Indo-Pacific Command said the missile launches highlight "the destabilizing impact" of North Korea's unlawful weapons programs. It said the U.S. commitments to the defence of South Korea and Japan "remain ironclad."

North Korea's state media said long-range artillery units on its western coast fired two rounds cross-country toward the eastern waters on Monday morning, possibly referring to the same activity its neighbours said were missile launches. The official Korean Central News Agency said the North Korean artillery rounds simulated strikes on targets up to 395 kilometres (245 miles) away.

The North said the launches involved its new 600-millimetre multiple rocket launcher system that could be armed with "tactical" nuclear weapons for battlefield use. Some experts viewed the weapons system as a short-range ballistic missile.

"The frequency of using the Pacific as our firing range depends upon the U.S. forces' action character," Kim Yo Jong, the powerful sister of North Korean leader Kim Jong Un, said in a statement carried by state media. "We are well aware of the movement of U.S. forces' strategic strike means, (which are) recently getting brisk around the Korean Peninsula."

Calling the United States "the worst maniacs," she threatened to take unspecified "corresponding counteraction" in response to the future moves by the U.S. military. She could be referring to the U.S. flyover of B-1B long-range, supersonic bombers on Sunday for separate training with South Korea and Japan. The B-1B deployment came as a response to North Korea's launch of the Hwasong-15 ICBM off its east coast on Saturday in the country's first missile test since Jan. 1.

North Korea is extremely sensitive to the deployment of B-1B bombers, which can carry a huge payload of conventional weapons.

North Korea's state media said Sunday the ICBM test was meant to further bolster its "fatal" nuclear attack capacity and verify the weapon's reliability and the combat readiness of the country's nuclear force. In her earlier statement Sunday, Kim Yo Jong threatened to take additional powerful steps over upcoming military drills between the United States and South Korea.

North Korea has steadfastly slammed regular South Korea-U.S. military drills as a practice for a northward invasion though the allies say their exercises are defensive in nature. Some observers say North Korea often uses its rivals' drills as a pretext to hone and perfect its weapons systems.

The South Korean and U.S. militaries plan to hold a tabletop exercise this week to hone a joint response to a potential use of nuclear weapons by North Korea. The allies are also to conduct another joint computer-simulated exercise and field training in March.

Hours after Monday's launches, South Korea's Foreign Ministry said Seoul placed unilateral sanctions on four individuals and five institutions it said were involved in illicit activities supporting the North's nuclear arms development and evasion of sanctions. While South Korean President Yoon Suk Yeol's government has so far placed sanctions on 31 individuals and 35 organizations for supporting the North's nuclear ambitions, such steps are seen as mostly symbolic considering the lack of business activities between the rivals.

North Korea has claimed to have missiles capable of striking both the U.S. mainland and South Korea with nuclear weapons, but many foreign experts have said North Korea still has some key remaining technologies to master, such as shrinking the warheads small enough to be mounted on missiles and ensuring those warheads survive atmospheric reentry.

In her statement Monday, Kim Yo Jong reiterated that North Korea has re-entry vehicle technology. She also hit back at South Korean experts who questioned whether North Korea's ICBMs would be functional in real-war situations.

Kim Yo Jong insisted that the nine hours of launch preparation time after her brother Kim Jong Un ordered it included the efforts of sealing the launch site and evacuating people and was not long because of shortcomings of the missile system itself.

Last year, North Korea set an annual record with the launch of more than 70 missiles. North Korea has said many of those weapons tests were a warning over previous U.S.-South Korean military drills. It also passed a law that allows it to use nuclear weapons preemptively in a broad range of scenarios.

Kim Jong Un entered 2023 with a call for an "exponential increase" of the country's nuclear warheads, mass production of battlefield tactical nuclear weapons targeting South Korea and the development of more advanced ICBMs targeting the U.S.