North Korea fired two ballistic missiles off the east coast on Friday, hours after the Biden administration warned of toppling the Kim Jong-un regime should it launch nuclear attacks against the United States and its allies in its unveiled nuclear strategy.

The South Korean military “detected two short-range ballistic missiles being fired from the area of Tongchon County in Kangwon Province toward the East Coast between around 11:59 a.m. and 12:18 p.m. local time” on Friday, according to the Joint Chiefs of Staff.

The short-range ballistic missiles traveled about 230 kilometers at a speed of Mach 5 and an altitude of around 24 km, the JCS said in a statement, adding that South Korean and US intelligence authorities are analyzing the specifications.

The two missiles traveled a short distance at a low altitude. In general, it is more challenging to detect and intercept missiles fired at lower altitudes.

The South Korean military reportedly braced for the possibility of North Korea firing solid-propellant short-range ballistic missiles including KN-23, 24, and 25 dual-capable missiles. North Korean leader Kim Jong-un may have observed the missile launches.

The missiles targeted Al Island, an uninhabited island in the East Sea, a South Korean military official who wished to remain anonymous confirmed.

“Our military will maintain a firm readiness posture while tracking and monitoring related moves in preparation for further provocations by North Korea in close coordination with the US,” the JCS said.

South Korea’s JCS strongly condemned the ballistic missile launches and urged North Korea to immediately stop its ballistic missile launches. They are a grave provocation that undermines the peace and stability of the Korean Peninsula, the international community, and is a flagrant violation of the UN Security Council resolutions, it said.

National security adviser Kim Sung-han convened an emergency meeting of the National Security Council standing committee to discuss countermeasures to North Korea’s missile launches, the South Korean presidential office said.

President Yoon Suk-yeol was immediately briefed on the launches, deputy presidential spokesperson Lee Jae-myoung said on Friday.

The NSC strongly condemned Pyongyang’s ballistic missile launches as a provocation that violates the UN Security Council resolutions.

The NSC members also pointed out that the missile launches on Friday came after recent repeated ballistic missile launches and violations of the Sept. 19 inter-Korean Comprehensive Military Agreement.

North Korea breached the inter-Korean military reduction deal on several occasions this month. North Korea’s merchant ship intruded over the Northern Limit Line, the de facto inter-Korean maritime boundary, in the West Sea.

The NSC members also “agreed to keep close tabs on the possibility of North Korea conducting a strategic provocation including an intercontinental ballistic missile launch and nuclear test.”

South Korea’s National Intelligence Service on Wednesday said North Korea may conduct a seventh nuclear test before the US midterm elections on Nov. 8.

The missile launch also came around 12 hours after the Biden administration warned the Kim Jong-un regime of the “dire consequences” of using nuclear weapons in the Nuclear Posture Review, a document on the US’ defense strategy.

The Pentagon on Thursday released the report along with two other policy documents, the National Defense Strategy and Missile Defense Review.

“Any nuclear attack by North Korea against the United States or its allies and partners is unacceptable and will result in the end of that regime,” the NPR read. “There is no scenario in which the Kim regime could employ nuclear weapons and survive."

The Biden administration also pointed out that “North Korea can also conduct rapid strategic attacks in East Asia” without using nuclear weapons. But the unveiled NPR said the “United States nuclear weapons continue to play a role in deterring such attacks” in the contingency scenario, leaving open the option of using nuclear weapons against non-nuclear attacks.

North Korea also launched two ballistic missiles on the last day of the 12-day annual Hoguk field training exercise led by the South Korean military. The US forces also took part in the Hoguk defense drills led by South Korea’s JCS to enhance interoperability with South Korean counterparts.

In addition, South Korea and the US are set to publicly stage large-scale aerial drills, involving their F-35 stealth fighters, next week to enhance combat readiness and train for wartime contingencies amid mounting threats from North Korea. 

The Vigilant Storm exercise will be conducted from Oct. 31 to Nov. 4 in South Korean airspace, South Korea’s Air Force said on Friday. 

Seoul and Washington will mobilize a total of 240 combat aircraft. The South Korean Air Force plans to dispatch 140 aircraft such as F-35A stealth fighters, F-15K and KF-16 fighter jets and KC-330 tankers. The US Air Force will deploy around 100 aircraft, including F-35B stealth fighters, EA-18 electronic warfare aircraft, KC-135 tankers and Lockheed U-2 reconnaissance aircraft.

South Korea’s F-35A stealth fighters and the US’ F-35B stealth fighters will team up for the first time during the Vigilant Storm exercise.

The Kim Jong-un regime has justified its recent spate of missile launches and artillery firings as countermeasures against defense-oriented combined exercises that South Korea and the US have staged regularly.

North Korea fired 13 ballistic missiles and two cruise missiles in nine discrete launches in 18 days from Sept. 25 to Oct. 14.

In addition, North Korea fired around 920 artillery shells toward inter-Korean maritime buffer zones from Oct. 14 to 24. Seoul has denounced such artillery firing as a “flagrant violation of the Sept. 19 military agreement.” The two Koreas agreed to cease all live-fire and maritime maneuver exercises in the buffer zones in a military tension reduction deal signed during an inter-Korean summit on Sept. 19, 2018.