Israeli strikes across Gaza killed scores overnight as battles raged Sunday in the besieged territory's south and Hamas was reviewing a proposal for a halt in the nearly four-month-long war.

The head of Iraq's pro-Iran Hashed al-Shaabi alliance on Sunday demanded the withdrawal of U.S.-led coalition forces from the country following deadly strikes.

The U.S. military overnight launched an air assault on dozens of sites in Iraq and Syria used by Iranian-backed militias and the Iranian Revolutionary Guard, in the opening salvo of retaliation for the drone strike that killed three U.S. troops in Jordan last weekend.

The massive barrage of strikes hit more than 85 targets at seven locations, including command and control headquarters, intelligence centers, rockets and missiles, drone and ammunition storage sites and other facilities that were connected to the militias or the IRGC's Quds Force, the Guard's expeditionary unit that handles Tehran's relationship with and arming of regional militias. And President Joe Biden made it clear in a statement that there will be more to come.

Hamas officials said that the group is studying a proposed cease-fire deal that would include prolonged pauses in fighting in Gaza and swaps of Israeli hostages for Palestinian prisoners, but the militants appeared to rule out some key components.

Hamas remains committed to its initial demands for a permanent cease-fire, the group's top political leader Ismail Haniyeh and a senior Beirut-based official, Osama Hamdan, said. Hamdan also said the group seeks the release of thousands of Palestinian prisoners being held for acts related to the conflict with Israel, including those serving life sentences.

The U.S. military launched an air assault on dozens of sites in Iraq and Syria used by Iranian-backed militias Friday, in the opening salvo of retaliation for the drone strike that killed three U.S. troops in Jordan last weekend, officials told The Associated Press.

President Joe Biden and other top U.S. leaders have been warning for days that the U.S. would strike back at the militias, and they made it clear that it wouldn't be just one hit, but would be a "tiered response" over time. The officials spoke on condition of anonymity to discuss military operations not yet made public.

Three pro-Iran fighters were killed in Israeli strikes south of Damascus Friday, a war monitor said, with Iranian media reporting an adviser from the Revolutionary Guards was among the dead.

The Syrian Observatory for Human Rights said "three members of pro-Iran groups, including an Iranian and an Iraqi" were killed in "Israeli air strikes".

Iraq's pro-Iran Al-Nujaba movement said Friday it intends to press on with attacks on U.S. troops in the Middle East, despite Washington's threat to hit back after three of its soldiers were killed in Jordan.

"Any (U.S.) strike will result in an appropriate response," Al-Nujaba leader Akram al-Kaabi said in a statement, adding the group would continue its actions until its demands are met for U.S. troops to leave Iraq and an end to Israel's war on Hamas in Gaza.

Defense Secretary Lloyd Austin has said it's time to further disable Iran-backed militias that have struck at U.S. forces and ships in the Middle East and the U.S. is preparing to take significant action in response to the deaths of three U.S. service members in Jordan.

For days the U.S. has hinted strikes are imminent. While the threat of retaliation for Sunday's deaths has driven some militant groups to say they were stopping hostilities, as late as Thursday Yemen's Houthi rebels were still attacking vessels and fired a ballistic missile at a Liberian-flagged container ship in the Red Sea.

President Joe Biden on Thursday issued an executive order that targets Israeli settlers in the West Bank who have been accused of attacking Palestinians and Israeli peace activists in the occupied territory, imposing financial sanctions and visa bans in an initial round against four individuals.

Those settlers were involved in acts of violence, as well as threats and attempts to destroy or seize Palestinian property, according to the order. The penalties aim to block the four from using the U.S. financial system and bar American citizens from dealing with them. U.S. officials said they were evaluating whether to punish others involved in attacks that have intensified during the Israel-Hamas war.

Satellite photos show new demolition along a 1-kilometer-deep path on the Gaza Strip's border with Israel, according an analysis by The Associated Press and expert reports. The destruction comes as Israel has said it wants to establish a buffer zone there, over international objections, further tearing away at land the Palestinians want for a state.

The demolition along the path represents only a sliver of the wider damage from the Israel-Hamas war seen in Gaza, which one assessment suggests has damaged or destroyed half of all the buildings within the coastal enclave.