Ammon News - The United States is telling its citizens to leave Lebanon and is deploying more military might in the Middle East as preventative and defensive measures, Jonathan Finer, White House National Security Council deputy adviser, said on Sunday, according to Reuters.

Regional tensions have soared following the assassination of Ismail Haniyeh, Hamas' top leader, in Tehran on Wednesday, a day after an Israeli strike in Beirut killed Fuad Shukr, a senior military commander from the Lebanese group Hezbollah, which is backed by Iran.

Secretary of State Tony Blinken told his counterparts from the G7 countries on Sunday that an attack by Iran and Hezbollah against Israel could start as early as Monday, three sources briefed on the call tell Axios.

Blinken convened the conference call to coordinate with close U.S. allies and try to generate last-minute diplomatic pressure on Iran and Hezbollah to minimize their retaliation as much as possible. He stressed that limiting the impact of their strikes is the best chance to prevent all-out war.

Iran and its Lebanese ally Hezbollah have vowed to respond to the assassinations by Israel of Hamas political leader Ismail Haniyeh in Tehran and Hezbollah military commander Fuad Shukr in Beirut.

The sources said Blinken stressed that the U.S. believes Iran and Hezbollah will both retaliate.

Blinken said the U.S. doesn't know the exact timing of the attacks but stressed it could start as early as the next 24-48 hours — meaning as early as Monday, the sources said.

The secretary of state told his counterparts the U.S. is making efforts to break the escalatory cycle by trying to limit the attacks by Iran and Hezbollah as much as possible and then restrain the Israeli response.

Blinken asked the other foreign ministers to apply diplomatic pressure on Iran, Hezbollah and Israel to maintain maximum restraint.

Blinken told the G7 foreign ministers that the boosting of U.S. forces in the region was for defensive purposes only, the sources said.