The United States is deploying additional military force to the Middle East as a defensive measure aimed at de-escalating tensions in the region, a White House official said.

Regional tensions have been rising following the assassination of Hamas political bureau chief Ismail Haniyeh on Wednesday in Tehran, a day after an Israeli airstrike on the southern suburbs of the Lebanese capital Beirut killed Hezbollah military commander Fuad Shukr and a number of civilians, including women and children.

There are growing fears that Israel's 10-month-old war on the Gaza Strip could escalate into a wider conflict in the Middle East. Iran and Hamas have blamed Israel for Haniyeh's killing in the Iranian capital, and have vowed, along with Hezbollah, to avenge it. Israel has neither claimed nor denied responsibility, but there is little doubt that Israel was behind the assassination.

US Secretary of State Antony Blinken told his G7 counterparts on Sunday that Iran and Hezbollah could begin attacking Israel as early as Monday, Axios reported, citing three sources familiar with the call. But Blinken, according to Axios, said it was unclear how Iran and Hezbollah would attack and he did not know the exact timing.

The Foreign Ministry said in a readout of the call that the ministers discussed "the urgent need to de-escalate in the Middle East."

The White House said Sunday evening that US President Joe Biden will hold a phone call with Jordan's King Abdullah II, and will also hold a meeting at the White House with his national security team to discuss the latest developments.

The Pentagon said Friday it would deploy additional fighter jets and Navy warships to the region.

“The overall goal is to lower the temperature in the region, deter and defend against those attacks, and avoid regional conflict,” Jonathan Finer, the White House deputy national security adviser, said on CBS’s “Face the Nation” on Sunday.

Wiener added that the United States and Israel are preparing for all possibilities.

Finer said a regional war was “very close” in April, when Iran launched drone and missile attacks on Israel after what it called an Israeli strike on its consulate in Damascus on April 1 that killed seven Islamic Revolutionary Guard Corps officers in the Syrian capital. Finer said the United States wants to be prepared in case such a situation arises again.

"This is not a prediction of future events. This is wise planning for them and for our government," Feiner said on CBS.

In a call with his Israeli counterpart, the Pentagon said US Defense Secretary Lloyd Austin affirmed US support for Israel's security and "its right to defend itself against threats from Iran, Lebanese Hezbollah, the Houthis, and other Iranian-backed terrorist groups."

The State Department said Blinken spoke with Iraqi Prime Minister Mohammed Shia al-Sudani on Sunday and stressed "the importance of all parties taking steps to de-escalate regional tensions, avoid further escalation, and promote stability."

The statement regarding the call, a copy of which was received by Al-Quds, indicated, "Secretary of State Antony Blinken spoke today with Iraqi Prime Minister Mohammed Shia al-Sudani to discuss the latest developments in the region. The Secretary stressed the importance of all parties taking steps to de-escalate regional tensions, avoid further escalation, and promote stability."

The statement added: “The Secretary also affirmed the United States’ commitment to the Higher Military Committee process to determine how and when the coalition’s military mission against ISIS in Iraq will transition and the importance of force protection as we work toward that transition. The Secretary affirmed that we remain committed to the comprehensive U.S.-Iraq relationship to build economic opportunity and prosperity for all Iraqis.”

US President Biden expressed hope on Saturday that Iran would back down despite its threat to avenge Haniyeh's killing.