By Nidal al-Mughrabi and Emily Rose
GAZA/JERUSALEM (Reuters) -Fears that the Israel-Palestinian conflict might spread through the Middle East ratcheted higher on Sunday, with the U.S. sending more military assets to the region as Israel pummelled targets in Gaza and elsewhere.
More than 50 Palestinians were killed in Israeli air strikes on the narrow coastal enclave overnight, Gaza medical sources said on Sunday.
An Israeli missile attack targeted Damascus and Aleppo international airports in neighbouring Syria early on Sunday, killing a civilian worker and putting the airports out of service, Syrian state media reported.
Israel said its aircraft struck Hezbollah targets in Lebanon on Saturday and that one of its soldiers was hit by an anti-tank missile in cross-border fighting that the Iran-backed group said killed six of its fighters.
U.S. Secretary of State Antony Blinken cautioned Lebanon's caretaker Prime Minister Najib Mikati on Saturday that the Lebanese people would be affected if his country were drawn in, the State Department said.
Israel started its "total siege" of Gaza after an Oct. 7 cross-border attack on southern Israel by militants of the Islamist movement Hamas killed 1,400 people, mainly civilians, in a shock rampage that has traumatised Israel.
Gaza's Health Ministry said on Saturday that Israel's air and missile strikes in retaliation had killed at least 4,385 Palestinians, including hundreds of children, with more than a million of the tiny territory's 2.3 million people displaced.
INCREASING ATTACKS
Defense Secretary Lloyd Austin said Washington would send more military assets to the Middle East to support Israel and strengthen the U.S. defence posture in the region following "recent escalations by Iran and its proxy forces".
A Terminal High Altitude Area Defense (THAAD) system and additional Patriot air defence missile system battalions will be sent to the region, and more troops will be put on standby, Austin said.
Washington has already sent a significant amount of naval power to the Middle East in recent weeks, including two aircraft carriers, their support ships and about 2,000 Marines.
Drones and rockets targeted two military bases housing U.S. forces in Iraq last week, the latest in a series of attacks after Iraqi militants warned Washington against intervening to support Israel against Iran-backed Hamas in the Gaza Strip.
A deadly blast at the Al-Ahli hospital in Gaza on Tuesday was likely caused by an errant rocket fired from Gaza, not an Israeli strike, Canada's National Department of Defence said, reaching similar conclusions to the U.S. and France.
Israeli aircraft struck a compound beneath a mosque in the Jenin refugee camp in the occupied West Bank early on Sunday that the military said was being used by militants to organise attacks.
Israeli forces killed a fifth Palestinian in the West Bank overnight, bringing the number of deaths there to 90 since the war began, the Palestinian health ministry said on Sunday.
Palestinian media reported at least 11 Palestinians were killed in an Israeli strike in the southern Gaza city of Khan Younis, and that Israel was striking the southern city of Rafah.
The strikes came hours after Israeli military spokesperson Rear Admiral Daniel Hagari called on Gazans to move south out of harm's way.
"For your own safety move southward. We will continue to attack in the area of Gaza City and increase attacks," Hagari told Israeli reporters on Saturday.
AID ARRIVES, INVASION LOOMS
The first humanitarian aid convoy allowed into the enclave since war broke out arrived through the Rafah border crossing on Saturday. The United Nations said the 20-truck convoy brought life-saving supplies that would be received by the Palestinian Red Crescent.
But the U.N. humanitarian office said the volume of goods that entered on Saturday was just 4% of the daily average of imports into Gaza before the hostilities and a fraction of what was needed after 13 days of siege of the crowded enclave.
Biden, long a firm supporter of Israel, cheered the arrival of the aid after days of intense negotiations. He said the United States was committed to ensuring more aid gets to Palestinians running out of food, water, medicines and fuel.
"We will continue to work with all parties," Biden said in a statement.
Israel has amassed tanks and troops near the fenced border around Gaza for a planned ground invasion aiming to annihilate Hamas, after several inconclusive wars dating to its seizure of power there in 2007.
"We are going to go into the Gaza Strip... to destroy Hamas operatives and Hamas infrastructure," Chief of Staff Lieutenant General Herzi Halevi told troops in a video distributed by the Israeli military on Saturday. "We will have in our mind the memories of the images and those who fell on Saturday two weeks ago."
(Reporting by Nidal al-Mughrabi in Gaza, Michelle Nichols in New York, and the Washington and Jerusalem Bureaus; Writing by Phil Stewart and Lincoln Feast; Editing by Daniel Wallis and William Mallard)