Government officials did not immediately confirm the reports, but authorities in one town told AFP they were suspending a drill planned for next week on orders from Tokyo.
The decision comes after US President Donald Trump and North Korea's leader Kim Jong Un met last week in Singapore, with the pair signing a joint document calling for denuclearisation of the Korean peninsula.
Yaita in Tochigi prefecture north of Tokyo had been planning an evacuation drill for next week involving some 800 residents including 350 school children, city official Yutaka Yanagida told AFP.
But the city suddenly cancelled all preparations late Wednesday after being instructed by the government that "drills should be postponed for the time being following a change in the environment after the US-North Korea summit," he said.
Contacted by AFP, a Cabinet Office official said the government would announce its policy on evacuation drills on Friday, declining to comment further.
Earlier this year, hundreds of Tokyo residents scrambled for cover in the Japanese capital's first evacuation drill for a military attack by Pyongyang.
North Korea has singled out Japan, a key US ally in the region, for verbal attacks, threatening to "sink" the country into the sea and to turn it into "ashes".
But the regional mood has turned towards diplomacy since the Winter Olympics hosted by South Korea, which set off a series of diplomatic moves culminating in the Trump-Kim meet.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)