IDF Chief of Staff Lt. Gen. Benny Gantz said Tuesday the military was still operating “on the working assumption” that three Israeli teenagers kidnapped in the West Bank are still alive, “but with the passing of time, fears grow.”

Israeli students Eyal Yifrach, 19, Gil-ad Shaar, 16, and Naftali Fraenkel 16, were kidnapped in the West Bank on June 12. Israeli forces have managed a massive manhunt for the three and their kidnappers while also cracking down on the Hamas movement, which Jerusalem says is responsible.

Gantz’s comments seemed to clash with those of Defense Minister Moshe Ya’alon, who said earlier Tuesday it was “only a matter of time” before the teens would be found.

“We are making progress all the time,” Ya’alon said of the search for the missing teenagers. “We are not working in the dark. It is only a matter of time till we get to the hostages and the kidnappers, but we need patience.”

Twelve days into the search, Israel’s security forces have made no breakthrough, an Israeli army spokesman acknowledged on Tuesday afternoon.

Speaking to The Times of Israel as the cabinet voted to scale down the operation, spokesman Lt. Col. Peter Lerner stressed that “we expect the mission [to find the three teens] to continue,” and reiterated that Israel was certain that Hamas was behind the June 12 abduction. But despite almost two weeks of a feverish hunt, as a top priority both for the intelligence hierarchy and for forces on the ground, “we’ve not had a breakthrough in either area.”

Hamas has denied involvement.

Lerner said Operation Brother’s Keeper, which has seen some 350 alleged terrorists arrested in the West Bank, most of them Hamas members, was also aimed at making clear to Palestinian terror groups “that it isn’t in their interests to do this,” and noted that the security forces’ focus on Hamas also encompassed “the civilian organizations through which Hamas recruits” its members.

Military sources have also noted recently that 64 kidnap attempts had been thwarted in the past 18 months. The June 12 kidnapping evidently involved considerable sophistication and pre-planning, said one official, noting that it was “unprecedented” to have three Israelis abducted by terrorists — “but we get them all in the end.”

While acknowledging the precedents of Israelis seized in the West Bank being killed by their abductors, the sources reiterated that the IDF’s working assumption is that the three are alive, and said that the nature and scale of the search “reflects that belief and hope.”

On Tuesday afternoon the cabinet voted to significantly reduce the security forces’ West Bank presence and limit the scope of Operation Brother’s Keeper, aimed at finding three kidnapped teens, to intelligence-gathering campaigns seeking direct ties to the abduction.

The decision came amid raised concerns that a continued IDF crackdown during the Ramadan holiday would spark riots, Army Radio reported, and in light of increased international scrutiny and criticism of the operation, now in its twelfth day. Thousands of troops have been deployed in the West Bank, searching homes and other sites mainly but not solely in the Hebron area, and making more than 300 arrests.

Israeli forces withdrew from the center of Hebron, where they had been concentrating their operation, but were still blocking off roads around the city and were stationed in large numbers a short distance outside, security sources told AFP Tuesday.

Middle East Quartet envoy Tony Blair said Tuesday he was “deeply troubled by the ongoing events” and Palestinian deaths.

“Israel must act with restraint when operating in populated Palestinian areas – including Gaza – and ensure that civilians are not harmed,” he said in a statement,” calling for a limit on restrictions on movement and access in the West Bank.

French Foreign Minister Laurent Fabius condemned the alleged kidnappings, but implored Israel to “respect international law… and use proportional force” in its arrests.

AFP contributed to this report