In an apparent first, North Korea launched a ballistic missile Wednesday morning that fell into waters inside Japan’s exclusive economic zone in the Sea of Japan, South Korean and Japanese authorities said.

The missile was launched from South Hwanghae province in the southwest of the country at around 7:50 a.m., South Korea’s Joint Chiefs of Staff said.

In Tokyo, Defense Minister Gen Nakatani told reporters that the missile flew around 1,000 km and appeared to have landed in Japan’s EEZ 250 km west of Akita Prefecture’s Oga Peninsula.

If confirmed, this would be the first time for such a missile to land in Japan’s EEZ, according to the Defense Ministry. In 1998, a piece of the nose cover of a Taepodong-1 missile that the North launched over Japan fell into the nation’s EEZ in the Pacific Ocean.

The U.S. Strategic Command said it detected the simultaneous launch by the North of two missiles in the morning, one of which exploded immediately after launch.

“The second was tracked over North Korea and into the Sea of Japan,” it said in a statement.

Yonhap news agency, quoting a military source, said the missile was a medium-range Rodong, which has an estimated range of up to 1,300 km, making it capable of reaching as far as Japan.

Prime Minister Shinzo Abe called the launch a “grave threat to Japan’s security” and a “reckless act that is difficult to forgive.”

He added that his government will “resolutely respond in cooperation with the United States and South Korea.” Tokyo issued a strong protest to Pyongyang via Japan’s embassy in Beijing.

“(The launch) is in defiance of clear U.N. Security Council resolutions and is an extremely problematic act from the standpoint of securing the safety of aircraft and vessels at sea,” the government said in a statement.

Nakatani ordered the Self-Defense Forces to gather information on the launch and continue its surveillance of the relevant airspace and waters.

Chief Cabinet Secretary Yoshihide Suga said Friday the Maritime Self-Defense Force is searching for fragments of the missile, adding that there were no reports so far of damage caused to aircraft or ships.

In Washington, a U.S. State Department spokeswoman condemned the launch, saying such provocations would only “increase the international community’s resolve to counter” North Korea’s actions.

A series of North Korean missile launches and attempted launches since the start of the year have raised concern in Japan, South Korea and the U.S.

The launches follow last month’s announcement by South Korea and the United States of their decision to set up a new missile defense system — the Terminal High Altitude Area Defense system — in South Korea to counter the North’s rising threat.

North Korea has also conducted four nuclear tests, most recently in January, despite U.N. Security Council resolutions prohibiting the act and warnings from the international community.