Japan has lowered its alert level for North Korean ballistic missile launches amid diminishing tensions following the historic summit between the U.S. and North Korean leaders last month, government sources said Monday.

As a result, the Maritime Self-Defense Force's Aegis vessels, which are equipped with Standard Missile-3 interceptors, will no longer remain in the Sea of Japan as previously, the sources said. But the vessels will still be prepared to intercept missiles within about 24 hours if signs of a possible launch are detected.

The government, meanwhile, will keep in place a standing order issued to the Self-Defense Forces in 2016 to shoot down any projectile heading toward Japanese territory.