(Bloomberg) —North Korea conducted another missile test early Monday as Kim Jong Un’s regime continued to defy sanctions against nuclear weapons development and escalate tensions on the Korean peninsula.

The missile, which appears to be a SCUD variant, was fired at 5:39 a.m. from Wonsan off North Korea’s east coast and flew 450 kilometers (280 miles) toward Japan, according to South Korean and Japanese military officials.

Japan’s Chief Cabinet Secretary Yoshihide Suga said the projectile may have fallen into waters in Japan’s exclusive economic zone. He called North Korea’s action an “extreme” problem from the viewpoint of the safety of aircraft and ships in the zone and a “clear” violation of United Nations Security Council resolution banning such weapons testing.

A National Security Council spokesman says the U.S. government is aware of reports of North Korea’s missile launch and that President Donald Trump has been briefed.

If confirmed to be a ballistic missile, it would be the North’s ninth this year as Kim accelerates his nuclear weapons program.

North Korea has stepped up its missile tests in recent weeks, and on May 14 it launched a new rocket that analysts estimate could travel as far as Guam. Trump has said military action is an option to prevent Kim’s regime from developing missiles that could carry a nuclear warhead to North America.

South Korean President Moon Jae-in called a meeting of the national security council. Moon came to office earlier this month pledging to engage with Kim’s regime to bring peace to the peninsula.

North Korea tested a rocket on May 14 that it said could carry a “large-size heavy nuclear warhead” over long distances. The Hwasong-12 was estimated to have a range of at least 4,500 kilometers, putting it within reach of U.S. military facilities on the island of Guam.

A week later, it fired another missile, the medium-range Pukguksong-2, which Kim has approved for deployment and mass production, according to the state-controlled news agency KCNA. The missile is powered by solid fuel, potentially making it easier to fire quickly from a mobile launcher that could avoid detection.

Trump, who has said all options are on the table to deal with Kim’s regime, has sought more help from China to rein in its neighbor and ally. Acting Assistant Secretary of State Susan Thornton on Friday acknowledged China’s efforts such as banning North Korean coal imports and tightening border controls, while adding that “they clearly have to do more.”

North Korea has so far this year refrained from conducting a nuclear test. The isolated nation has performed five nuclear trials since 2006, three of which took place under Kim, who took power after the death of his father Kim Jong Il in 2011.