North Korea launched a long-range ballistic missile into the sea off its east coast on Saturday, after warning of a strong response to an upcoming U.S.-South Korean military exercise, Reuters reported.

Japanese authorities said the missile landed in waters inside Japan's exclusive economic zone more than an hour after launch, suggesting it was one of the DPRK's largest missiles. 

Nuclear-armed North Korea has fired an unprecedented number of missiles last year, including intercontinental ballistic missiles (ICBMs). 

Saturday's long-range missile was launched from the Sunan area near Pyongyang, the South Korean military said. Sunan is the site of Pyongyang International Airport, where North Korea has conducted most of its recent ICBM tests.