As the search for three kidnapped teens entered its fourth day Monday, Israeli officials were considering a number of measures to place extra pressure on the Hamas terror group, which it has fingered in the abduction.

Israeli forces arrested 40 Hamas members overnight Sunday, including a number of senior lawmakers, bringing the total number of detainees since the kidnapping to 150, the IDF said in a statement Monday morning.

The government is reportedly weighing the option of expelling senior West Bank Hamas leaders to the Gaza Strip.

Officials in the Justice Ministry discussed on Sunday whether such a move would be legal under international law and would hold up against scrutiny at Israel’s High Court of Justice, a senior Israeli official told Haaretz. Others measures mulled included demolishing the homes of senior Hamas operatives and sanctions against Hamas members currently in Israeli prisons, the paper reported.

“We have a purpose, and that is to find these three boys and bring them home, and to strike Hamas as hard as possible, and that’s what we’ll do,” IDF Chief of Staff Benny Gantz said Sunday during a late-night situation assessment. “We’re on our way to a significant operation.”

Economy Minister Naftali Bennett on Sunday evening did not confirm plans to expel Hamas members, or any other concrete measures the government was considering, but hinted at steps intended to hurt the organization.

Those responsible for the abduction of Eyal Yifrach, 19, Gil-ad Shaar, 16, and Naftali Frenkel, 16, will “have to pay,” Bennett said. “It needs to hurt them, and they need to know that we will locate whoever is behind this, whoever planned and executed this, so that they’ll regret it.”

The cabinet was looking at “very many different options,” he said.

Defense Minister Moshe Ya’alon hinted Sunday that Israel, either in retribution or in order to thwart future attacks, may reestablish its campaign of targeted killings against the organization’s leadership. “We will know how to exact a very heavy price from the leaders of Hamas wherever and whenever we find it appropriate and from whomever ponders the notion of harming the citizens of Israel or disrupting their lives,” Ya’alon said at the Israel Defense Prize ceremony at the President’s Residence in Jerusalem.

Prime Minister Benjamin Netanyahu and Deputy Foreign Minister Ze'ev Elkin at a Likud party meeting in the Knesset, July 2013. (photo credit: Miriam Alster/Flash90)

Prime Minister Benjamin Netanyahu and Deputy Foreign Minister Ze’ev Elkin at a Likud party meeting in the Knesset, July 2013. (photo credit: Miriam Alster/Flash90)

MK Ze’ev Elkin, the new chairman of the Knesset’s powerful Foreign Affairs and Defense Committee, called on the government to re-arrest the 1,027 Palestinian security prisoners Israel released in the 2011 exchange for abducted Israeli soldier Gilad Shalit, and the 78 prisoners released in the framework of the recently stalled peace process.

“The time has come for us to turn the equation and change the rules of the game. The terrorists need to know that these criminal kidnappings are putting terrorists in jail rather than bringing about their release,” he said Sunday in an interview with Channel 2, and has since repeated that message in other media and on Facebook.

The security cabinet was scheduled to meet Monday afternoon to discuss Israel’s next steps.

Mitch Ginsburg contributed to his report.