A group of more than 600 former Israeli security officials urged President Donald Trump on Wednesday to press for the full disarmament of Hamas and to support Palestinian Authority involvement in any future administration of Gaza, seeking to influence his upcoming meeting with Prime Minister Benjamin Netanyahu.

The appeal came in a letter sent by Commanders for Israel’s Security, a group that includes former senior Israeli security officials, ahead of Trump’s expected Dec. 29 meeting with Netanyahu at Mar-a-Lago. In the letter, CIS argues that Hamas’ disarmament must be paired with steps to legitimize postwar governance in Gaza, including a phased Israeli security withdrawal and a role for the Palestinian Authority in implementing the second phase of Trump’s Gaza peace plan.

CIS, which counts former heads of the Mossad, the Shin Bet internal security agency, the Israeli military, the Israel Police and former ambassadors among its members, has previously urged Trump to intervene diplomatically. Last August, the group sent an open letter calling on him to pressure Israel to immediately end the war in Gaza.

In its letter, CIS argued that for Trump’s Gaza plan to succeed, “the disarmament process must be synchronized with measures that enhance its [the process’s] legitimacy and contribute to overall stability.” The group said this should include signals that Israel’s security presence in Gaza would be phased out as progress is made in disarming Hamas.