Israel announced Monday that it will free 26 more Palestinian prisoners convicted of killing Israelis, saying it was fulfilling its commitment to U.S. diplomats as part of ongoing peace negotiations, despite intense opposition within Prime Minister Benjamin Netanyahu’s cabinet.

Netanyahu agreed months ago to free 104 Palestinian militants as part of a deal brokered by Secretary of State John F. Kerry to get the Palestinian Authority, which governs the West Bank, to the negotiating table. Many of the prisoners were serving life sentences for killing Israeli civilians in the late 1980s and early 1990s.

The first group of 26 prisoners was released in August, triggering an emotional outpouring among the families of those they had killed.

All the Palestinians slated to be freed this week were convicted of killing Israelis and have spent 19 to 28 years in Israeli prisons. The majority are from the West Bank. Five are from the Gaza Strip, governed by the Islamist group Hamas, which does not recognize Israel.

Among the prisoners who will be freed is Omar Issa Masoud, convicted of murdering Ian Feinberg, a lawyer who had been working in Gaza to help improve the economic conditions of Palestinians. Feinberg, 30, was slain in April 1993, when gunmen stormed an aid meeting in Gaza City that he was attending.

Another prisoner on the list is Hazem Kassem Shbair, convicted of murdering Holocaust survivor Isaac Rotenberg at a construction site where the two worked together. The Almagor Terror Victims Association in Israel said that most of Rotenberg’s family had been killed during World War II but that he managed to escape, arriving in Israel in 1947. Rotenberg was bludgeoned to death with an ax in 1994, when he was 67.

Parliament member David Tsur of the left-leaning Hatnua party told Ynetnews.com that he considered the release of such prisoners “improper conduct” and would have preferred that the government instead offer the Palestinians the carrot of halting settlement construction in the West Bank. “Releasing terrorists is irreversible,” Tsur said.

Economy and Trade Minister Naftali Bennett, head of the right-wing Jewish Home party and the third most powerful member of Netanyahu’s government, tried to stop the prisoner release, saying it was “a dubious privilege” to have Israeli negotiators sit with their Palestinian counterparts.

But Netanyahu said the government must abide by its commitments. “The decision to free prisoners is one of the most difficult I made as prime minister,” he said, according to accounts in the Israeli news media. “This decision was necessary in our current reality. We have to navigate through a complex international arena full of challenges.”

Palestinian Authority President Mahmoud Abbas is planning to welcome the freed prisoners in a celebration in Ramallah late Tuesday, officials said.

Critics of the release were given fresh ammunition after two missiles were fired from the Gaza Strip into Israel early Monday. No one asserted responsibility, and no one was injured. One missile was intercepted by Israel’s U.S.-funded Iron Dome missile defense system above the coastal city of Ashkelon. The other rocket landed in an uninhabited patch of land nearby.

The Israeli air force retaliated with an attack on two clandestine rocket launchpads north of Gaza City.

Hard-line Israeli politicians opposed to the prisoner release — and to negotiations that would give away land for a future Palestinian state — said the rocket fire showed that there was no trustworthy partner for peace on the Palestinian side.

Parliament member Miri Regev of Netanyahu’s Likud party said that in return for releasing prisoners, Israel sees “rocket fire, murder and terror.”

On Sunday, two mortar rounds were fired at Israel from Gaza. And earlier this month, Israel’s military shut down a “terror tunnel” that led from the Palestinian territory into the Jewish state.

Lt. Col. Peter Lerner, a spokesman for the Israel Defense Forces, said the tunnel was designed to facilitate attacks on Israel, such as the kidnapping of Israeli troops, the planting of explosive devices or the moving of militants across the border.

Israel’s decision to strike the concealed rocket-launch sites Monday “shows our capability and our knowledge,” Lerner said, and puts Hamas on notice about Israel’s intent to respond to any provocations with force.

Matthew Levitt, a scholar at the Washington Institute for Near East Policy and an expert on Hamas and the Lebanese militia Hezbollah, said Israel usually holds Hamas responsible for rockets fired from Gaza and described a retaliatory strike as “par for the course.”

Israeli aircraft pounded rocket-­launch sites in response to rocket fire Aug. 14, Israeli officials said, and hit targets in Gaza on June 24, April 28 and April 3.

“The real question,” Levitt said, is why the rockets continue to be fired from Gaza, despite the relative calm in the area. He said the answer might be linked to Gaza’s increasing isolation, after the ouster of the Islamist government of President Mohamed Morsi in neighboring Egypt.

Since removing Morsi in a coup, Egypt’s military has destroyed or sealed most of the smuggling tunnels between Egypt and Gaza and has repeatedly shut down a pedestrian crossing into Gaza at Rafah.

Those moves denied Hamas its “tax revenue” from the tunnels, further battered the weak Gazan economy and effectively sealed off the coastal enclave.