(TWP) North Korea on Tuesday claimed it had successfully tested an intercontinental ballistic missile, a potential milestone in its campaign to develop a nuclear-tipped weapon capable of hitting the mainland United States.

In a special announcement on state television, North Korea said it launched a Hwasong-14 missile that flew 579 miles, reaching an altitude of 1,741 miles.

South Korean President Moon Jae-in had earlier said it may have been an ICBM; U.S. Pacific Command’s first statement on test called it an “intermediate range” missile.

Whatever the final determination, Tuesday’s news will renew questions about the rapid development of weapons that Trump, as president-elect, vowed to stop.

It also looks set to put North Korea back at the top of the president’s agenda, most immediately at Group of 20 meetings in Germany this week.

As news of the test broke, but before North Korea claimed it was an ICBM, Trump took to Twitter, calling out North Korean leader Kim Jong Un and appearing to once again urge China to do more to pressure him.

“North Korea has just launched another missile. Does this guy have anything better to do with his life?” Trump wrote.

“Hard to believe that South Korea and Japan will put up with this much longer,” he continued. “Perhaps China will put a heavy move on North Korea and end this nonsense once and for all.”

Japanese Prime Minister Shinzo Abe appeared to share Trump’s frustration, if not his tone. In remarks to the press, he vowed to work closely with the United States and South Korea, but called on China and Russia to do more.

“I’d like to strongly urge international society’s cooperation on the North Korea issue and urge China’s chairman, Xi Jinping, and Russia’s President Putin to take more constructive measures.”

In a daily press conference, Geng Shuang, a spokesman for China’s Foreign Ministry, condemned the test but countered that Beijing had “spared no effort” in its fight.

Analysts are still looking for clues about the missile and what those clues might mean, both in terms of North Korea’s capability and the international community’s response.

U.S. and South Korean officials say the launch was made from a site in North Korea’s Phyongan province. The missile flew more than 500 miles — a very long way — before landing in waters off Japan’s coast.

Melissa Hanham, a North Korea expert at the James Martin Center for Nonproliferation Studies in California, said the launch appeared to be a test of range.

Many press reports have noted that the test showed that North Korea has the ability to hit Alaska. That is strictly true in terms of range, Hanham said, though they have yet to test components necessary for such a hit.

“The missile as it was shot only shows the distance, it doesn’t prove the re-entry vehicle would have held out on its way to Alaska,” she said.

Still, she said, this is a “huge milestone” for the North Koreans.

The landmark launch comes after a string of recent tests, including a salvo of missiles last month and three tests in May alone. Kim has now launched more missiles in one year than his father did in 17 years in power.

The rate and variety of tests have alarmed experts who see each step as part of a march toward a more serious threat to the continental United States.

“Is this particular ICBM going to hit D.C.? No. But are they working toward it? Yes,” Hanham said.

Since taking office, Trump has made North Korea’s weapons program a priority, focusing his efforts — and tweets — on getting North Korea to back down.

At the heart of Trump’s strategy is getting China, North Korea’s neighbor and patron, to pressure Kim and cut off resources.

In recent weeks, there have been signs that is frustrated with China’s progress. On June 21, Trump tweeted that, although he appreciated Beijing’s efforts, “it has not worked out.”

John Delury, an Asia expert at Seoul’s Yonsei University, said there may now be a political imperative for Trump to downplay the significance of the latest test and North Korea’s ICBM claim.

Trump “set an implicit red line,” Delury said, “and it doesn’t look good if the North Koreans skipped across the line when he wasn’t looking, especially after a tweet that played it down.”

Kim, meanwhile, will want to play up the test to bolster his domestic credibility and send a signal to the United States, South Korea and Japan.

In North Korean, Tuesday’s launch was hailed as a historic triumph.

“The success in the test-fire of intercontinental ballistic rocket Hwasong-14 is a powerful manifestation of the invincible state might and the tremendous capability of the self-reliant national defense industry of the DPRK,” read one North Korean account, according to Chinese state media.

“It is also a great auspicious event to be specially recorded in the history of the DPRK.”