North Korea demonstrated its growing military capabilities with the launch of four ballistic missiles Monday, three of which fell into the Sea of Japan, in what Prime Minister Shinzo Abe characterized as “a new level of threat.”

Officials said the North fired the barrage at around 7:34 a.m. Japan time from near North Korea’s Donchang-ri long-range missile site.

The Defense Ministry said they flew about 1,000 km and reached a height of about 260 km, with three of the missiles falling within Japan’s exclusive economic zone, 300 km to 350 km west of the Oga Peninsula in Akita Prefecture. The fourth missile fell near the EEZ, which extends 200 nautical miles (370 km) from Japan’s coastline.

During Monday’s Upper House Budget Committee session, Abe condemned the provocation as “utterly intolerable” and noted the North’s accelerating technological advancements.

“(The test-firing) clearly shows that North Korea is now a new level of threat,” Abe said.

The prime minister also said that “Japan will continue to coordinate closely with the United States, South Korea and other countries to strongly urge North Korea to exercise restraint.”

Although this is not the first time that North Korean missiles have fallen within Japan’s EEZ, a high-ranking official said that because four missiles were apparently fired simultaneously from the same location, the move represents a grave danger to Japan’s national security. In September, the North fired three ballistic missiles that also fell within Japan’s EEZ, some 200 km to 250 km off Okushiri Island, Hokkaido.

Monday’s salvo prompted officials in Tokyo to hold a National Security Council meeting to discuss responses.

After the NSC meeting, Chief Cabinet Secretary Yoshihide Suga said the government had already lodged protests with Pyongyang — using the “strongest terms” — through the embassy in Beijing. Suga added that it is natural that the international community will seek even tougher responses given that the North has ignored numerous United Nations resolutions.

Following the launch, Kenji Kanasugi, head of Asian and Oceanian affairs in the Foreign Ministry, and Joseph Yun, U.S. special representative for North Korea policy, confirmed by telephone that they will closely coordinate bilaterally as well as multilaterally with South Korea and the U.N. to urge North Korea to halt further provocations.

South Korea is likely to intensify its push to isolate the North diplomatically by seeking its suspension from global bodies such as the U.N.

“After completing an analysis and assessment of the North’s missile tests, the government will likely come out with a much tougher countermeasure with regards to such issues as suspending the North’s membership in the U.N.,” the Yonhap news agency quoted an anonymous South Korean government official as saying.

The test could also add momentum to calls by U.S. lawmakers to return Pyongyang to a list of state sponsors of terrorism.

Monday’s barrage came as Pyongyang continues to show off its advances in nuclear weapons and missile technology. Less than three weeks ago, the North defiantly test-fired a new type of medium-range missile that is believed to use solid fuel. The launch came during Abe’s first summit talks with U.S. President Donald Trump.

Experts say solid-fueled missiles represent more of a threat than their liquid-fueled counterparts as they requires less preparation time.

There has been growing speculation that the North will conduct an intercontinental ballistic missile (ICBM) test after Kim Jong Un used a New Year’s Day address to claim that Pyongyang was in the final stages of developing a long-range missile capable of hitting New York and Washington. South Korea’s military said Monday that none of Monday’s missiles appeared to have been ICBMs.

Experts agreed, saying that the launch appeared to be similar to ones conducted last year.

“Although we cannot be 100 percent certain what type of missiles were fired until we get images from KCNA, the range and apogee would indicate they are closer to an extended range Scud or Rodong missile used in a salvo launch,” said David Schmerler, a researcher at the Center for Nonproliferation Studies at the Middlebury Institute of International Studies. “We saw launches like this last year off of Reunification Highway near Hwangju.”

Sebastian Maslow, an assistant professor of political science at the Tohoku University School of Law in Sendai, said it’s too early to determine what the launches mean in terms of the North’s quest to field a missile capable of hitting the continental U.S.

“I would not jump to any conclusion as to what this missile launch suggests with regard to the DPRK’s ICBM program, but (rather it appears to be) a test of U.S., Japan and ROK response capabilities detecting and projecting the missile’s trajectory, intelligence sharing, and coordination of any likely response,” Maslow said, using the acronyms for the two countries’ formal names, the Democratic Republic of Korea and the Republic of Korea.

The timing of the launches also raised questions among regional observers.

They overlapped with annual South Korean-U.S. military exercises known as Foal Eagle, drills that Pyongyang regards as a prelude to invasion. The launches also came right after the opening of China’s rubber-stamp parliament in Beijing — a gathering aimed at highlighting President Xi Jinping’s command over foreign and domestic affairs.

“We may speculate that the launches may be intended to test China’s further willingness of confronting the DPRK” as the Communist Party’s leadership gathers for its annual meeting, Maslow said.

For Abe, the timing of the missiles’ splashdown in Japan’s EEZ appeared fortuitous. The prime minister has been grappling with a scandal surrounding a nationalist kindergarten’s shady land deal that is allegedly linked to his office.

The launch, Maslow said, could help Abe shift attention from the scandal to national security issues.

“No doubt, Abe and his Liberal Democratic Party will amplify the DPRK missile and nuclear program and North Korea threat narrative in the coming days and weeks to highlight the importance of U.S.-Japan security cooperation, and the need to expand Japan’s missile defense program, including THAAD (Terminal High Altitude Area Defense system) as part of the bilateral security framework.”

The U.S.-made THAAD system is due to be deployed to South Korea later this year. Japan is also reportedly considering bringing in the system.

Monday’s launch also came as the Trump administration is reportedly considering a harder-line approach to the North’s provocations. Trump’s national security deputies have reviewed in recent meetings a range of options to counter the North’s missile threat, The New York Times reported Sunday. Options include direct missile strikes on its launch sites and the possibility of reintroducing nuclear weapons to the South, The Times said.

Those options will soon be presented to Trump and his top national security aides, the report said, quoting U.S. administration officials.

In Washington, the State Department condemned the launches, vowing that the U.S. was ready to “use the full range of capabilities at our disposal against this growing threat.”

“We remain prepared — and will continue to take steps to increase our readiness — to defend ourselves and our allies from attack, and are prepared to use the full range of capabilities at our disposal against this growing threat,” acting spokesman Mark Toner said in a statement.

The test-firing also occurred amid growing international pressure on Pyongyang after the assassination of North Korean leader Kim Jong Un’s half brother Kim Jong Nam, who was allegedly killed by Indonesian and Vietnamese women using the deadly VX nerve agent. It is widely speculated that the Kim Jong Un himself ordered the assassination.

“The North probably wants to deflect the international attention on this issue with the test-fire, as it has denied its involvement in the assassination,” said Hideshi Takesada, a professor at Takushoku University and an expert on North Korea.

The international community has been piling pressure on the North after it conducted two nuclear tests and launched 23 missiles last year — almost twice as many as it did under the rule of Kim Jong Un’s father, Kim Jong Il.

The U.N. last year adopted what Japanese officials call “the toughest sanctions” to date against North Korea, including a ban on coal imports from the country.

The efficacy of the sanctions, however, largely depends on China, which is Pyongyang’s biggest economic partner. Beijing announced last month that it was halting coal imports from the North until the end of this year.

“We will have to see how Japan and the rest of the international community reacts, but my feeling is that looking at all the recent developments … Japan and others will have to find some way to take defensive measures and impose costs on North Korea,” said Daniel Pinkston, an East Asia expert at Troy University in Seoul.

“In my view, failure to do so invites more North Korean belligerence. … THAAD and more missile defense cooperation by Japan should be expected,” he added.

Information from Kyodo added