Israel has intensified its diplomatic and security campaigns against Hamas, and is also calling on Turkey to shut down the group’s activities and offices in the country. These calls come after a Nov. 21 terror attack in Jerusalem’s Old City, perpetrated by a member of Hamas who had contacts with Hamas seniors in Turkey, and following the exposure of a large Hamas cell in the West Bank, also affiliated with operatives of the group in Istanbul.

Israel’s public broadcasting Kan channel reported after the attack in Jerusalem, in which 26-year-old Eliyahu David Kay was killed and four other Israelis wounded, that the gunman had traveled to Turkey several times in recent months. Security agencies said that during these trips the gunman, Fadi Abu Shkhaydam, met with senior Hamas officials, who guided his plans. Family members of Shkhaydam denied that, claiming he flew to Istanbul to meet with his son who studies in the country and to inspect real estate he owns there.

Shortly after the Jerusalem attack, on Nov. 22, the Shin Bet revealed that in recent weeks it had arrested over 50 members of a sophisticated Hamas cell in the West Bank.

The security agency said that the cell was in advanced stages of planning major terror attacks both in the West Bank and in Israel. The Shin Bet seized weapons, materials for at least four explosive belts for suicide attacks and an undisclosed amount of money. Israeli security officials said the cell was managed by Hamas politburo deputy Saleh al-Arouri, and by another senior Hamas member, Zacharia Najib. Both men live in Turkey, at least partly.