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The US on Sunday said it feared an escalation of the war between Israel and Hamas and the prospect of Iran getting directly involved.
Speaking on CBS, White House National Security Adviser Jake Sullivan cited the possibility of a new battle front on the Israel-Lebanon border.
“We can't rule out that Iran would choose to get directly engaged some way," he said. "We have to prepare for every possible contingency.
“That's a risk that we have been mindful of since the start,” Mr Sullivan said of the prospect of Iran getting involved in the war, which was triggered by the Hamas attack on southern Israel from Gaza last weekend.
“It's why the President moves so rapidly and decisively to get an aircraft carrier into the eastern Mediterranean, to get aircraft into the Gulf, because he sent a very clear message to any state or any actor that would seek to exploit this situation."
Defence Secretary Lloyd Austin announced the deployment of a second aircraft carrier on Saturday “to deter hostile actions against Israel or any efforts towards widening this war following Hamas's attack”.
In the eastern Mediterranean the carrier USS Eisenhower and its accompanying ships will join the USS Gerald R Ford, which was sent after the Hamas attack on October 7.
Iran on Sunday warned any Israeli ground offensive in the Gaza Strip could escalate conflicts elsewhere in the Middle East.
“No one can guarantee the control of the situation and the non-expansion of the conflicts,” an Iranian Foreign Ministry statement read.
The Israeli army told the Shiite militant group Hezbollah to closely watch what is happening to Hamas and warned its militants against “crossing the threshold”.
Israeli Defence Minister Yoav Gallant on Sunday said Israel has no interest in waging war on its northern front and that if Lebanese group Hezbollah restrains itself, Israel would respect the situation on the border as it is today.
Hezbollah has claimed responsibility for several rocket attacks on northern Israel since the war between Israel and Hamas erupted.
"Of course Iran is broadly complicit and this has helped Hamas function and be able to conduct the terrorist attack they have conducted," John Kirby, spokesman for the National Security Council said on Fox News.
But he reiterated the US position that it has no intelligence pointing to specific Iranian participation in the Hamas attack.