Japanese police are investigating phone calls threatening to kill U.S. Ambassador Caroline Kennedy, ABC news reported.
Authorities said Wednesday that Tokyo's metropolitan police were investigating the calls to the U.S. Embassy in Tokyo.
They said the embassy had also received similar calls targeting Alfred Magleby, the consul general based on the southern island of Okinawa, home to about half of the 50,000 American troops based in Japan.
The embassy declined to comment.
Japanese media reports said the death threats came last month from a caller speaking in English and that police were looking into the case on suspicion of blackmailing. No other details, including motives, were known.
Earlier this month, the U.S. ambassador to South Korea was knifed by an anti-U.S. activist and had to be hospitalized for several days.