North Korea launches short-range missile U.S. officials said they are monitoring the situation.

 -- North Korea launched what appears to be a short-range Scud missile, which flew about 280 miles into the Sea of Japan, on Sunday, according to the South Korean military and U.S. officials. The launch was the ninth missile test conducted by North Korea this year.

"U.S. Pacific Command detected and tracked what we assess was a North Korean missile launch at 10:40 a.m. Hawaii time May 28," said a statement from U.S. Pacific Command. "The launch of a short range ballistic missile occurred near Wonsan Airfield.

"The missile was tracked for six minutes until it landed in the Sea of Japan," said the statement.

"We are working with our interagency partners on a more detailed assessment. We continue to monitor North Korea's actions closely," the statement continued.

"It is assumed to be a Scud missile. The missile flew 450 km (280 miles), and more details are now being analyzed," the South Korean military said. A U.S. defense official also said the missile appeared to be a short range Scud missile.

Earlier, the South Korean military said South Korean President Moon Jae-in ordered a National Security Council meeting to discuss the latest North Korean launch.

The ballistic missile test is the ninth such test conducted this year, in the third weekend in a row that North Korea has launched a missile.

President Donald Trump responded on Monday to the missile test.

Japan's Defense Ministry reported it was possible that the North Korean missile landed in the Sea of Japan inside Japan's economic exclusion zone, which stretches 200 miles from its shoreline.

On March 5, North Korea fired four Scud missiles, which traveled more than 600 miles into the Sea of Japan, and three of them landed in Japan's economic exclusion zone.

Scud missiles are not a concern to U.S. officials because they are short range and are based on a decades-old, Soviet-era technology.

However, North Korea's two most recent missile tests have demonstrated significant progress of its missile program. North Korea has stated that it is seeking to develop a long-range missile armed with a nuclear warhead capable of striking the continental United States.

On May 14, North Korea fired what the U.S. calls a KN-17 medium-range missile, which reached an unprecedented altitude of 2,000 kilometers (1,245 miles). That launch demonstrated that the missile could travel a similar distance horizontally.

On May 21, North Korea successfully launched a KN-15 solid-fuel missile, which flew more than 300 miles into the Sea of Japan. That launch has raised concerns because solid-fuel missiles are more stable than liquid-fuel missiles and can be fired on short notice.

"We always assume that, with a testing program, they get better with each test," Defense Secretary Jim Mattis said in an appearance on CBS' "Face the Nation."

ABC News' Katherine Faulders contributed to this report.