TEL AVIV, Israel (AP) — The fragile ceasefire in the Israel-Hamas war was tested Tuesday as the slower-than-hoped return of deceased hostages from Gaza prompted an Israeli military agency to declare a “violation” of the truce agreement that it would respond to by halving the number of trucks allowed to bring humanitarian aid into the devastated territory.

Word of the cut in aid was transmitted to U.S. officials and international aid groups, according to three AP sources who spoke on the condition of anonymity to discuss the matter. The Israeli government did not immediately comment.

A day earlier, Israelis celebrated the return of the last 20 living hostages in Gaza and Palestinians rejoiced at Israel’s release of some 2,000 prisoners and detainees as part of the ceasefire’s first phase.

But now attention in Israel has turned to when Hamas will return all the bodies of hostages who died in captivity. While Israeli officials had understood there could be some delay in the recovery effort, the families of hostages and their supporters expressed dismay that only four of the 28 bodies were returned on Monday.

The Hostages Family Forum, a grassroots organization representing many of the hostage families, called it a “blatant violation of the agreement by Hamas.” The top official in Israel coordinating the return of hostages and the missing, Gal Hirsch, told the families in a note that pressure was being applied on Hamas through international mediators to expedite the process. A copy of the note was seen by The Associated Press and its authenticity was confirmed by someone with knowledge of the statement.