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The US Navy is sending an aircraft carrier strike group to the Eastern Mediterranean, boosting air squadrons in the region, and will supply the Israel forces with materiel including munitions, Defence Secretary Lloyd Austin said on Sunday.
The strike group is led by the nuclear-powered USS Gerald R Ford aircraft carrier, and accompanied by several support vessels including guided missile cruisers and destroyers.
The news comes a day after Israel announced it was at war following an unprecedented attack by Hamas that has left hundreds dead and prompted the call-up of thousands of Israeli reservists.
Washington has received that reports that "several Americans" are among the dead, US Secretary of State Antony Blinken said.
“We’re working overtime to verify that,” Mr Blinken said on CNN. “At the same time, there are reports of missing Americans. We're working to verify those."
Mr Austin said the US has also taken steps to bolster air force F-35, F-15, F-16 and A-10 fighter aircraft squadrons in the region.
“In addition, the United States government will be rapidly providing the Israel Defence Forces with additional equipment and resources, including munitions,” the Pentagon chief said in a statement.
“The US maintains ready forces globally to further reinforce this deterrence posture if required.”
He said the first security assistance was on the move and would arrive within days.
The transfer of munitions to Israel is likely going to add strain to the Pentagon's supplies, which are stretched thin as it tries to provide for Ukraine's armed forces in their counter-offensive against Russia.
In January, the Pentagon reportedly started pulling ammunition from a stockpile it had in Israel and transferring it to Ukraine.
The Pentagon did not comment on supply strains.
“Strengthening our joint force posture, in addition to the materiel support that we will rapidly provide to Israel, underscores the United States' ironclad support for the Israel Defence Forces and the Israeli people,” Mr Austin said.
US President Joe Biden spoke earlier with Israeli Prime Minister Benjamin Netanyahu to express “deep sympathy for all those missing, wounded, and killed", the White House said.
“He pledged his full support for the government and people of Israel in the face of an unprecedented and appalling assault by Hamas terrorists", including taking families as hostages.
An unknown number of Americans are among the hostages that Hamas took as it attacked Israel from the Gaza Strip, the Israeli ambassador to the US said on Sunday.
Michael Herzog was asked on CBS News if there were Americans among the soldiers and civilians that the Palestinian militant group abducted in southern Israel.
“I understand there are but I don't have details,” he said.
Saturday's attack came as Israel and Saudi Arabia appear to be getting closer to making a historic deal to establish diplomatic ties. Mr Blinken said Hamas might have been trying to prevent that from happening.
“Certainly that could have been part of the motivation,” he said.
The Israel Gaza conflict – in pictures
