Tokyo will “strongly demand” an explanation from Washington about reported allegations that Japanese diplomats in the U.S. were among 38 “targets” of American spying activities, Chief Cabinet Secretary Yoshihide Suga said Monday.

Japan will lodge an inquiry through diplomatic channels with the U.S. about Sunday’s report by The Guardian, which quoted what it says is a top-secret U.S. National Security Agency document leaked by fugitive ex-NSA and ex-CIA contractor Edward Snowden.

The Guardian reported that one secret 2010 document lists 38 embassies and missions in New York and Washington that were described as “targets.” Among them were those of Japan, as well as Middle Eastern countries, the European Union mission, France, Italy, Greece, Mexico, South Korea, India and Turkey.

The British paper also reported on a 2007 document about a bugging method known as “Dropmire” that was “implanted on the Cryptofax at the EU Embassy, DC,” an apparent reference to a wiretap placed in a commercially available encrypted fax machine used at the mission.

Asked if Tokyo will independently check its communications equipment and other facilities in Japanese offices in the U.S., Suga insisted Tokyo will make an inquiry to the U.S. side first.

“We are aware of the report, but it’s not clear (whether) what was reported was true,” Suga said, adding Tokyo “of course has concerns.”

“First we will demand the truth through diplomatic channels,” he said, stressing Japan has done its utmost to prevent eavesdropping at its embassies and other Japanese offices in the U.S.

“It’s common sense for any country in the world to be careful about such things,” he said. But since there is a limit to what Japan can do in the U.S., Tokyo is making inquiries to Washington, he said.

Suga’s subdued reaction probably reflected the basic diplomatic stance of Prime Minister Shinzo Abe, who is placing priority on strengthening the Japan-U.S. military alliance to keep China and other rivals in check.

On June 16, The Guardian, based on information from Snowden, also reported that the British government eavesdropped on the phone calls and email of senior government officials at the Group of 20 summit in April 2009 in London.

Soon after the June 16 report came out, a high-ranking Japanese official in Tokyo said he believes that the intelligence agencies of many countries, including those of the U.S., routinely engage in eavesdropping and other spying activities.

“Japan is not doing this but (many countries) are,” the official said, speaking on condition that he not be named.