Japan and the United States held joint military drills in the airspace over the Sea of Japan after North Korea fired a missile on Friday, Tokyo defence officials said.
The announcement came after Japan said the ballistic missile was believed to have landed in waters within the country's exclusive economic zone (EEZ) west of Hokkaido.
The EEZ extends up to 200 nautical miles from Japan's coastline, beyond the limits of its territorial waters.
"Japan Self-Defense Forces and US armed forces conducted a bilateral exercise... amid an increasingly severe security environment surrounding Japan," a joint staff statement distributed by the Japanese defence ministry said.
The tactical air drills followed "North Korea's ICBM-class ballistic missile launch that landed within Japanese Exclusive Economic Zone in the Sea of Japan", the statement said.
"This bilateral exercise reaffirms the strong will between Japan and the United States to respond to any situation," it added.
The exercise also "further strengthens the deterrence and response capabilities of the Japan-US Alliance", the statement said.
There are around 55,000 US military personnel stationed in Japan, most in the southern region of Okinawa, with air bases in suburban Tokyo and in the northern Aomori region.
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