US Senator Lindsey Graham on Sunday accused Iran of involvement in the October 7 Hamas attack and warned that any escalation of the war could exact a cost from Tehran.

"We're here today to tell Iran: 'We're watching you. If this war grows, it's coming to your backyard,'" Graham starkly warned during a visit to Tel Aviv, without elaborating on what that meant.

Although the warning seemed to be directed at the Lebanese Hezbollah, which can open a northern front against Israel, any such decision needs to be approved by Tehran, the backer of all Arab militant groups in the region.

"The idea that this happened without Iranian involvement is laughable," Graham said in what was a rebuttal to the Biden administration that after the Hamas attack said there is no direct evidence of Iran’s involvement.

Although President Joe Biden has acknowledged Iran’s continuous support for Hamas and Hezbollah, he said last week that “Iran constantly supports Hamas and Hezbollah …. [but] did they have foreknowledge, did they help plan the attack, there’s no evidence of that at this point.”

Last week, speaking on NBC News Sen. Graham had issued a warning to Iran. He vowed to introduce a resolution in the Senate to allow “military action by the United States in conjunction with Israel to knock Iran out of the oil business.”

The Iranian regime has praised Hamas for its “heroic” attack, denying that the militants killed civilians, and pledging to continue support. Some Iranian hardliner lawmakers have even threatened direct involvement and the closure of the Hormuz Strait in the Persian Gulf if the United States directly intervenes to support Israel.