Japan's Defense Ministry says the Air Self-Defense Force and the US Air Force conducted a joint drill on Sunday.
The ministry says a total of ten aircraft -- F-15 fighter jets from Japan and US B-1 bombers and F-16 fighters --took part in the exercise over the Sea of Japan.
It says Japan's Maritime Self-Defense Force and the US Navy also carried out a joint exercise with ships equipped with the Aegis missile-tracking system on Saturday and Sunday.
The participants reportedly checked procedures for sharing information when a missile is launched.
The Defense Ministry says Japan and the US reaffirmed their readiness to respond and strengthened the deterrence of their alliance, as the security situation surrounding Japan becomes increasingly severe.
The exercises were held after North Korea fired an intercontinental ballistic missile on Thursday. The North also launched a ballistic missile on Sunday.