The government's decision to release some 200 security prisoners - mainly from Fatah and including two with "blood on their hands" - to help Palestinian Authority President Mahmoud Abbas is opposed by the Shin Bet (Israel Security Agency), a senior defense official told The Jerusalem Post on Sunday. News of the impending release was received negatively among Shin Bet handlers and agents, the source said. "You have to hear the responses inside the Shin Bet to the release. They work day and night to capture and neutralize terrorists, and all of it is gone in an instant," he said. About 40 percent of security prisoners are released before completing their sentences, the defense source said. "People in the Shin Bet end up asking, 'Why do we capture these people? Where did all my work go? Where is the deterrence?'" He added that similar responses were heard in the corridors of judicial departments within the security forces. "A terrorist who plants an explosive device gets 10 years in prison but will end up being released after three or four years. This hurts the motivation in the Shin Bet," he said. The same source said he was sure that the government chose to go ahead with the prisoner release deal with Hizbullah in July because the chances of a similar deal with Hamas to free kidnapped soldier Gilad Schalit were very low. "The government realized it could not do a southern hostage deal, so it went with the northern hostage deal to reduce public pressure on it. The government knew that they [Eldad Regev and Ehud Goldwasser] were no longer alive. They figured that [child-killer Samir] Kuntar had been in prison for many years, and went for the deal. "Hamas is demanding 450 heavyweight prisoners who took part in recent terrorist attacks. The memories of the victims' families are still very raw. I don't believe the government can go ahead with this," the defense official said. The government's attempt to help Fatah with the new prisoner release was unlikely to succeed, Brig.-Gen. (res.) Shalom Harari, a senior research scholar with the Institute for Counter-Terrorism at the Interdisciplinary Center in Herzliya, said on Sunday. Harari, who was as a senior adviser on Palestinian affairs to the Defense Ministry for 20 years, said Fatah was in an extremely vulnerable state, and that the proposed prisoner release would likely be "forgotten after two days." Fatah's responses to previous prisoner releases were not encouraging, he said. "On the morning after the release, we heard Fatah blaming Israel. Whatever happens, they will blame Israel and fault everyone except for themselves," Harari said. "The aim of the release is also to show the Americans and Europeans that we are open-minded, and that we are helping out the side that we are supposed to be helping," he added. Around 20% of security prisoners engage in terrorism after being released, Harari said. "In the short term, this is not a risk - the Aksa Martyrs Brigades have been neutralized by the PA for the time being," he said, adding that Fatah might return to terrorism in the future. "But what many in Israel do not realize is that while these terrorists may not go back to fighting, many will go back to indoctrinating others into terrorism, and creating a terror-supporting environment," he added. "Some will recruit on campuses, others will become so-called 'journalists,' while others will be integrated into institutions or sent abroad. These jobs are meant to compensate them for the alleged suffering they underwent in prisons in Israel." Brig.-Gen. (res.) Shlomo Brom of Tel Aviv University's Institute for National Security Studies said the security risk from such a release was "very low." Brom, a former head of the Strategic Planning Division in the General Staff's Planning Branch, said the main obstacle to releases were the emotions experienced by victims' families by the release of terrorists with "blood on their hands." "The families' lobby seeks revenge, and opposes the releases," Brom said.