Two US fighter jets struck weapons and ammunition facilities in Syria on Friday in retaliation for attacks on US forces by Iranian-backed militia as concerns grew that the Israel-Hamas conflict may spread in the Middle East.

US President Joe Biden ordered strikes on the two facilities used by Iran’s Revolutionary Guard Corps and militia groups that it backs, the Pentagon said, warning the US will take additional measures if attacks by Iran’s proxies continue.

US and coalition troops have been attacked at least 19 times in Iraq and in Syria by Iran-backed forces in the past week. Hamas, Islamic Jihad and Lebanon’s Hezbollah are all backed by Tehran.

Iranian Foreign Minister Hossein Amirabdollahian said at the United Nations on Thursday that if Israel’s offensive against Hamas did not stop, the United States will “not be spared from this fire”.

The US air strikes took place at roughly 4:30 a.m. on Friday (0130 GMT) near Abu Kamal, a Syrian town on the border with Iraq, and were carried out by two F-16 fighter jets using precision munitions, a US defence official said.”These precision self-defence strikes are a response to a series of ongoing and mostly unsuccessful attacks against US personnel in Iraq and Syria by Iranian-backed militia groups that began on October 17,” US Defense Secretary Lloyd Austin said in a statement.

“These Iranian-backed attacks against US forces are unacceptable and must stop,” Austin said.

Biden has sent a rare message to Iranian Supreme Leader Ayatollah Ali Khamenei warning Tehran against targeting US personnel in the Middle East, the White House said earlier on Thursday.

“What we want is for Iran to take very specific actions, to direct its militias and proxies to stand down,” a senior US defence official said. The United States did not coordinate the air strikes with Israel, the official added.

The United States has sent warships and fighter aircraft to the region over the last three weeks. On Thursday the Pentagon said about 900 more US troops have arrived in the Middle East or are heading there to bolster air defences for US personnel.

Israel said on Friday military raids into Gaza were preparing “the next stage of the operation”, amid fears that a ground invasion of the Palestinian enclave could spark a wider Middle East conflict.

Israel has bombarded the densely populated Gaza Strip following the Oct. 7 Hamas attack on Israeli communities. Israel says Hamas killed some 1,400 people including children, and took more than 200 hostages, some of them infants and older adults.

The Hamas-controlled Gaza health ministry said on Thursday that 7,028 Palestinians had been killed in the retaliatory air strikes, including 2,913 children.

Reuters could not independently verify the tolls.

A missile launched as part of fighting between Hamas and Israel struck an Egyptian resort town about 220 km (135 miles) from the Gaza Strip early on Friday, Egypt’s Al Qahera News reported, citing sources.

The missile hit a medical facility in Taba, injuring at least six people, Al Qahera reported. A witness in Taba confirmed hearing an explosion and seeing smoke rising, but Reuters was not immediately able to identify the blast’s source.

Israel says hits Hamas commanders

Israel said on Friday that its fighter jets had struck three senior Hamas operatives who played significant roles in the Oct. 7 attack on Israel. They were commanders in the Daraj Tuffah Battalion, part of the Gaza City Brigade, Israel said.

There was no official announcement by Hamas.

Palestinian militants clashed with Israeli troops in at least two areas of the Gaza Strip on Friday, Hamas-affiliated media reported.

Reuters was unable to immediately confirm the reports.

As the plight of Palestinian civilians grows more desperate, the issue of whether to have humanitarian pauses or ceasefire agreements in the Hamas-run coastal enclave will come before the 193-member U.N. General Assembly on Friday in a draft resolution submitted by Arab states calling for a ceasefire.

Unlike in the Security Council where resolutions on Gaza aid failed this week, no country holds a veto in the General Assembly. Resolutions are non-binding, but carry political weight.

More than 613,000 people were estimated to have been made homeless by the Israeli bombardment of Gaza and were being sheltered by the United Nations agency for Palestinian refugees, UNRWA.

Israelis support for ground invasion dips, poll

Almost half of Israelis want to hold off on any invasion of Gaza, according to a poll published on Friday.

Asked if the military should immediately escalate to a large-scale ground offensive, 29% of Israelis agreed while 49% said “it would be better to wait” and 22% were undecided, the poll published in the Maariv newspaper said.

The daily said the results contrasted with its Oct. 19 poll that found 65% support for a major ground offensive.

Maariv said “it is almost certain that the developments on the matter of the hostages, which is now topping the agenda, have had a great impact on this shift (in opinion)”.

Hamas freed four hostages over the last week amid efforts by regional mediator countries to arrange a larger-scale release. Hamas says around 50 hostages have been killed in Israeli strikes on Gaza.