The Musudan missile has an estimated range of up to 4,000 km (2,500 miles), enough to hit South Korea, Japan and the US territory of Guam.
Pyongyang has not reacted to the news.
The country has made a number of missile-related tests this year, despite being banned by the UN from any use of ballistic or nuclear technology.
It comes amid concerns that the North may soon launch another long-range rocket or conduct a nuclear test.
The test took place near the north-western city of Kusong at 03:33 GMT on Saturday, the Pentagon said in a statement.