Japanese police are investigating phone calls threatening to kill U.S. Ambassador Caroline Kennedy and another American envoy, authorities said Wednesday.

The calls to the U.S. Embassy targeted Kennedy and Alfred Magleby, the U.S. consul general on the southern island of Okinawa, according to an Okinawa police official who spoke on condition of anonymity.

Kennedy, the daughter of the late President John F. Kennedy, arrived in Tokyo in November 2013 as the first woman to serve as U.S. ambassador to Japan. She was appointed by President Obama after helping with his reelection campaign.

Tokyo police declined to comment on the threats. State Department spokeswoman Jen Psaki said the U.S. government takes threats to American diplomats seriously. - AP