(CNN)Japanese authorities are investigating death threats against the American ambassador to Japan, Caroline Kennedy, according to Japanese media reports and international wire services.
Reports: Death threats against Amb. Caroline Kennedy in Japan
Local police are looking into phone calls placed last month to the U.S. Embassy in Tokyo threatening to kill Kennedy, according to local media reports. CNN could not immediately confirm the reports.
"We take any threats to U.S. diplomats seriously," said State Department deputy spokesperson Marie Harf. "We take every step possible to protect our personnel. We are working with the Japanese government to ensure the necessary measures are in place. We will not comment on the specific details of any threats or the steps we take to address them."
News of the threats come two weeks after the Mark Lippert, the American ambassador to South Korea, was slashed by an assailant wielding a 10-inch knife at an event in Seoul. Lippert is recovering from gashes to his face and wrist.
The reports emerged as First Lady Michelle Obama arrived in Japan on Wednesday for the first leg of a five-day trip to Japan and Cambodia focusing on the importance of girls' education.
Former President Bill Clinton was also in Japan on Wednesday, delivering a speech at a university in Tokyo alongside Kennedy.
Kennedy is the daughter of former President John F. Kennedy and niece of Sen. Robert F. Kennedy, who were both assassinated when she was a child.