North Korea test-fired a ballistic missile early Saturday but the launch failed just after liftoff, the U.S. military said, just hours after the top U.S. diplomat called on other nations to cut diplomatic and economic ties with Pyongyang.

U.S. Pacific Command said the launch was from near the Pukchang airfield, northeast of the capital.

The missile did not leave North Korean territory, it added.

In Tokyo, Chief Cabinet Secretary Yoshihide Suga said the government believes the apparent ballistic missile flew about 50 km (30 miles) to the northeast, only to fall to land inside North Korea.

Prime Minister Shinzo Abe, who is on a trip to the United Kingdom, instructed the government to collect the latest intelligence, ensure Japan’s maritime and air safety and prepare for any possible contingency, Suga said. The launch also prompted Tokyo to hold a National Security Council meeting, he added.

The launch “is a clear violation of U.N. Security Council resolutions, and we absolutely will not tolerate repeated provocations by North Korea,” Suga said, adding that Tokyo had already lodged a “strong” protest with Pyongyang via its embassy in Beijing.

Suga declined to clarify whether Tokyo believed the latest test-firing had ended in a failure, adding only that the government was in the process of analyzing details from a “comprehensive and technical” point of view.

He also did not say whether Tokyo had been briefed by Washington on what United States’ next steps will be to deal with the latest saber-rattling. He said only that Japan and the U.S. are in “close communication” and ready to coordinate policies.

Tokyo Metro shut down all of its subway lines from 6:13 to 6:17 a.m. — in apparent response to news of the launch — to “ensure the safety of passengers,” according to official records uploaded by the company.

This was the first time the company has taken such precautions, NHK reported. According to the public broadcaster, the firm discussed earlier this month what emergency steps to take in the event of a North Korean missile launch and determined that it would halt train operations for about “10 minutes” for the safety of passengers, apparently reflecting heightened concerns over the danger posed by the unpredictable North.

In one particularly worrisome development, the North conducted a near-simultaneous launch of four extended-range Scud missiles in March as a part of what it said was a rehearsal for striking U.S. military bases in Japan.

North Korea is banned by multiple U.N. Security Council resolutions from conducting nuclear and missile tests, and is already subject to international sanctions.

In a two-sentence statement, the White House said President Donald Trump was aware of the test and had been briefed.

Taking to Twitter, Trump blasted Pyongyang over the launch, playing up China’s role in pressuring the North over its nuclear and missile programs. “North Korea disrespected the wishes of China & its highly respected President when it launched, though unsuccessfully, a missile today. Bad!”

Trump has repeatedly said China is key to solving the nuclear crisis.

But Chinese Foreign Minister Wang Yi, speaking ahead of the test, told a U.N. Security Council meeting on the issue that it was not only up to China to solve the North Korean problem. “The key to solving the nuclear issue on the peninsula does not lie in the hands of the Chinese side,” Wang said, according to media reports.

South Korea’s military confirmed the test-firing, with the Yonhap news agency reporting that the missile appeared to have blown up. The South’s Joint Chiefs of Staff said in a statement that the missile flew for several minutes and reached a maximum height of 71 km (44 miles) before it apparently failed, Yonhap reported.

Media reports, citing U.S. officials speaking on condition of anonymity to discuss sensitive matters, said the missile was likely a medium-range KN-17 ballistic missile. The North test-fired the same missile earlier this month in a launch that U.S. officials said also was a failure.

The KN-17 is believed to be a single-stage, short- to medium-range, liquid-fueled Scud or Rodong variant, with potential anti-ship applications.

The launch came as U.S. Secretary of State Rex Tillerson warned the United Nations that failure to rein in North Korea’s nuclear and ballistic missile programs would push Northeast Asia closer to conflict.

“With each successive detonation and missile test, North Korea pushes Northeast Asia and the world closer to instability and broader conflict,” Tillerson said. “The threat of a North Korean nuclear attack on Seoul, or Tokyo, is real.

“And it is likely only a matter of time before North Korea develops the capability to strike the U.S. mainland,” he told a meeting of the U.N. Security Council.

Tillerson proposed three ways of pressuring North Korea: U.N. member states should “fully implement” existing sanctions against Pyongyang, downgrade or suspend diplomatic ties with the country, and increase its financial isolation with new and tougher sanctions.

At the same meeting in New York, Foreign Minister Fumio Kishida reiterated Japan’s stance that the recent atomic and missile tests by the North pose “a new level of threats” and are “absolutely intolerable,” he said on the official Facebook page of the Foreign Ministry.

Japan, he wrote, called for a concerted effort by the international community to ramp up pressure on the pariah state.

Kishida also said he took the opportunity to hold ministerial meetings with his U.S., South Korean, Chinese and U.K. counterparts to discuss North Korea issues.

“Japan, the U.S. and the South Korea will closely coordinate and we will seek cooperation from China and Russia, which have significant influence over the North,” he said.

In an interview Thursday, Trump said that a “major, major conflict” with North Korea is possible over its nuclear and ballistic missile programs.

Tensions on the Korean Peninsula have hit a fever pitch as North Korea marked two key anniversaries this month.

In a show of force Friday, fighter jets from the Air Self-Defense Force linked up with aircraft from the USS Carl Vinson carrier strike group for joint drills in waters east of Okinawa as the U.S. vessel steamed toward the Sea of Japan.

Those exercises were held after a highly publicized two-day bilateral maritime exercise with the Vinson-led carrier group and MSDF ships as they transited the Philippine Sea on April 23 and 24.

Japanese officials have said more joint exercises are being considered.

On Saturday, Kyodo News quoted a Defense Ministry official as saying the Vinson was expected to reach the Sea of Japan later in the day along with Maritime Self-Defense Force vessels.

Once there, the aircraft carrier group will join the USS Michigan, a nuclear submarine that docked in South Korea on Tuesday. South Korea’s navy has said it will hold drills with the U.S. strike group.

The U.S. rerouted the Vinson strike group earlier this month to the Sea of Japan in an apparent bid to deter Pyongyang from further provocations.

So far, the North has conducted nine missile tests and is on target to match last year’s pace, according to a database compiled by the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies in Monterey, California.

Five of the tests were successful, according to the database.

Kent Boydston, an analyst focusing on the Korean Peninsula at the Peterson Institute for International Economics in Washington, said Saturday’s test was “part of North Korea’s continuing effort to normalize its provocations.”

“It’s worth noting that Pyongyang conducted a missile test but not a nuclear test, which would elicit a stronger response from the international community,” Boydston said.

While much attention has remained fixed on the North’s nuclear tests, its missile program likely poses the most immediate danger to the region.

Boydston said that despite the missile test’s apparent failure, Pyongyang would likely glean much from the launch.

“A failed missile test is still a banned missile test,” he said. “North Korea will learn and improve. Maybe the fact that it failed shouldn’t even be in the headline.”