Israel has increased security around Prime Minister Naftali Bennett’s family after a bullet was sent to them in the post.
The measures were put in place after “a letter with a death threat and a live bullet” was addressed to Mr Bennett and his family, his office said on Tuesday.
In response to the threat, Mr Bennett said no “political dispute” should lead to violence.
He also referred to his duty to protect his wife and four children, who have stayed in the family home rather than move to an official residence in Jerusalem.
Since Mr Bennett took office, security has been increased at the family property in Raanana, a usually quiet city to the north of Tel Aviv.
Israel has imposed a restriction order on reporting any details of the investigation, such as who is suspected of having posted the bullet.
Defence Minister Benny Gantz said the death threat against the prime minister crossed a “red line”, referring to a past assassination.
Prime minister Yitzhak Rabin was shot dead in 1995 at a political rally by an Israeli gunman who opposed a landmark peace deal signed with the Palestinians.