Several Israeli officials, whose names were quoted anonymously by a number of Israeli news outlets, seem to be increasingly skeptical about the success of Tuesday’s attack on Hamas’ Politburo leaders in Qatar’s capital, Doha, reports The Times of Israel.

“There is no indication at this time that the terrorists have been killed,” an anonymous source said, Channel 12 News reports. “We continue to hope that they have been killed, but optimism is fading.” Israeli public broadcaster Kan also reported similar sentiments. Journalist Ronen Bergman wrote on Ynet that two sources in the Israeli defense and intelligence communities told him that they were pessimistic about the strike being lethal to most, if not all, of the targets.

Bergman said the assessment of the military damage was ongoing. However, another source said that at least part of the mission had been accomplished: “to strike fear and terror into the hearts of Hamas’ political leaders.” Earlier, it was reported that six members of Hamas’ Politburo were killed in Tuesday’s Israeli strike on Doha. Hamas’ Politburo chief, Khalil al-Hayya, had survived the attack, but his son had died.