US officials in Washington and the Middle East said Friday that they were bracing for possible Iranian retaliation for the Israeli airstrike Monday in Damascus, Syria

Iran vowed Friday to avenge Israel's killing of senior commanders and other officers of its elite Quds Force, at a public funeral held for the dead men, elevating fears of open war but leaving unsaid how it would retaliate or when.

US military forces in the region have been placed on heightened alert. According to an Israeli official, Israel has also placed its military on high alert, canceled leave for combat units, recalled some reservists to air defense units and blocked GPS signals.

Two Iranian officials who asked not to be named because they were not authorized to speak publicly said that Iran had placed all its armed forces on full high alert and that a decision had been made that Iran must respond directly to the Damascus attack to create deterrence.

"Our brave men will punish the Zionist regime," Gen. Hossein Salami, commander in chief of Iran's Revolutionary Guard, told the crowd in Tehran, Iran, attending the funeral of the officers killed in Damascus. "We warn that no act by any enemy against our holy system will go unanswered, and the art of the Iranian nation is to break the power of empires."

The Israeli airstrike hit a building that was part of the Iranian Embassy complex in Damascus, killing three generals and four other officers of the Quds Force. The force, an arm of the Revolutionary Guard, conducts military and intelligence operations outside Iran, often working closely with allies that oppose Israel and the United States, including Syria, Hezbollah in Lebanon and Hamas.

There are precedents for a forceful response by Iran. Four years ago, after the United States killed the chief of the Quds Force, Maj. Gen. Qassem Soleimani, Iran fired missiles at US bases in Iraq, injuring more than 100 troops.

Although its proxy militias around the Middle East have launched a number of attacks on Israel since the war between Israel and Hamas began October 7, Iran has taken care to avoid a direct conflict that could lead to full-fledged war.

(With Agency Inputs)