TOKYO — Ukraine has asked Japan for satellite imagery, Nikkei has learned, as it tries to fend off invading Russian troops.

Ukraine is believed to be seeking high-resolution ground imagery to get a better grasp of the movements of Russian troops. Japan operates satellites with synthetic aperture radar (SAR) that can capture images day and night, and through clouds and other obstructions in the atmosphere.

Some of these satellites are owned by the government and others by private companies.

Japan’s government, not commercial satellite operators, is expected to make the decision, given as the imagery would be used for military purposes. The government will carefully take into account the situation in Ukraine in making the decision, sources said.

Use of Japanese satellite data is governed by the country’s remote sensing law. The sale of imagery to overseas customers is allowed under certain conditions but data will have to be encrypted to prevent usage by hostile groups.

The data request came directly from the Ukrainian government to Japanese SAR satellite operators, the sources said. Ukraine is also asking for image data owned by the Japanese government.

The Japan Aerospace Exploration Agency is the agency responsible for SAR satellite technology within the government.

Kyiv is also asking Western governments for satellite imagery. It wants to collect as much data as possible about Russian troop movements.

The Washington Post reported on March 10 that Ukrainian Deputy Prime Minister Mykhailo Fedorov asked U.S. satellite operators to share their imagery.

Japan earlier decided to provide Ukraine with bulletproof vests as part of emergency assistance.

There are worries that if Japan does provide the imagery, Moscow may see it as Tokyo becoming more involved in the war.