Japan moved to the highest possible alert level after North Korea fired four ballistic missiles simultaneously into nearby waters, the latest provocation from Kim Jong Un’s regime.

Three of the missiles fell into Japan’s exclusive economic zone, with one dropping about 350 kilometers west of the nation’s northern Akita prefecture, government spokesman Yoshihide Suga told reporters after a meeting of Japan’s National Security Council. Authorities were still analyzing the type of missile launched, he said.

The launches “clearly show that this is a new level of threat” from North Korea, Japanese Prime Minister Shinzo Abe told lawmakers in Tokyo. American officials held phone calls afterward with counterparts in Japan and South Korea, which rely on the U.S. for security.

“North Korea’s nuclear and missile capabilities have really improved, and they are becoming more difficult to predict,” Abe said. The missiles “are getting closer to Japan’s waters and territory.”

While North Korea routinely test-fires missiles — including more than two dozen last year — the timing of these launches is particularly sensitive. Tensions have escalated in recent weeks between China and South Korea over American plans to deploy a missile-defense system known as Thaad on the peninsula, part of measures to thwart Kim from gaining the ability to strike the continental U.S. with a nuclear warhead.

The launches also come as South Korea and the U.S. undertake annual military drills that Pyongyang has called a prelude to an invasion, and right after the start of the National People’s Congress in Beijing — a gathering aimed at showcasing President Xi Jinping’s command over foreign and domestic affairs.

Long-time allies China and North Korea had a rare public spat last month after Beijing banned coal imports last month after the death of Kim’s half-brother, Kim Jong Nam, in a Malaysia airport. Beijing accounts for more than 70 percent of its neighbor’s trade and provides food and energy aid.

The missiles, launched early Monday from the country’s northwest, flew around 1,000 kilometers (about 620 miles) into the East Sea, also known as the Sea of Japan, Roh Jae-cheon, spokesman for South Korea’s Joint Chiefs of Staff, told reporters in Seoul. There was a “low chance” the projectiles were intercontinental ballistic missiles, he said.

Kim Young-woo, a South Korean lawmaker and chairman of parliament’s National Defense Committee who was briefed by the JCS, said that the projectile looks similar to the Pukguksong-2 missile that North Korea test-fired last month.