WASHINGTON - The Pentagon says it detected and tracked a single North Korean missile launch and believes it was an intercontinental ballistic missile.

Pentagon spokesman Col. Rob Manning said Tuesday that the missile was launched from Sain Ni, North Korea, and traveled about 1,000 kilometers (about 620 miles) before landing in the Sea of Japan.

Manning says the Pentagon's information is based on an initial assessment of the launch. He says a more detailed assessment was in the works.

Japan's chief Cabinet secretary says North Korea has fired a missile that might have landed inside the country's exclusive economic zone in the Sea of Japan.

Yoshihide Suga says the missile appears to have been fired from North Korea's western coast and the government is gathering information and analyzing the launch data.

Suga says repeated provocation by the North is unacceptable and Tokyo has lodged a strong protest.

A U.S. official says this is the first missile launch North Korea has conducted in more than two months.
  
The Pentagon on Tuesday was more cautious, calling it a "probable" missile launch. Col. Rob Manning, a spokesman said, "We detected a probable missile launch from North Korea" at approximately 1:30 p.m. EST. He said the Pentagon is assessing the situation and has no further information to provide.
  
It would be the first North Korean missile test since it launched an intermediate-range ballistic missile on Sept. 15 that flew over northern Japan and into the Pacific Ocean.
  
The Yonhap news agency is reporting that North Korea has launched a ballistic missile.