US intelligence has intercepted orders from Iran to militants based in Iraq to attack American sites should a strike on Syria go through, US officials said Friday.

The intercepted message came from the head of the Revolutionary Guards’ Quds Force, Kassem Sulemenai, and went to Iranian-supported Shi’ite militia groups in Iraq, according to US officials cited in a report in the Wall Street Journal.

The targeted sites could include the US embassy in Baghdad and other American interest sites in the Iraqi capital, as well as the US embassy in Beirut and other sites in Lebanon via the terror group Hezbollah, the Journal reported.

The US remains on alert for an array of reprisal threats across the region, officials said, including a fleet of Iranian fast boats in the Persian Gulf, where American warships are positioned. Several destroyers and an amphibious warship are also stationed in the eastern Mediterranean, and US officials told the Journal that military resources have been moved around in preparation for a possible strike and any retaliation on the part of Syria or Iran.

On Thursday, the US Navy’s top admiral said the four destroyers are “fully ready” for a range of possible courses of action.

According to the report, the US has also readied Marines and other assets for the evacuation of military compounds and other sites should the need arise, and made preparations to against attacks on US embassies and diplomatic missions across the Middle East and North Africa.

On Wednesday, a Senate panel approved a resolution authorizing President Barack Obama to order a limited military strike in Syria in response to the regime’s alleged use of chemical weapons in an attack on a Damascus suburb in the early hours of August 21 — an attack which the US says killed 1,429 people. The conditions for the approval include that the operation last no more than 90 days and that there will be no American boots on the ground.

Obama will next be seeking congressional approval for a strike, as Congress reconvenes September 9. The president has already received public support for the move by leading Republican figures such as Senator John McCain, and House Speaker John Boehner.

The delay in a US strike could provide increased opportunities for those allied with Iran and Syria to coordinate retaliation attacks, warned US officials cited in the Journal report.

On Wednesday, Sulemenai said Iran would defend Syria “until the end,” according to a report in the Fars news agency. He reportedly added that the majority of Syrian rebels are foreigners and that the US has attempted repeatedly to topple Assad, unsuccessfully.

Iran has also threatened to hit Israel should the US carry out a strike, with the commander of the Revolutionary Guards’ General Mohammad Ali Jafari saying late last month that a possible war in Syria “will result in the imminent destruction of the Zionist regime of Israel.”

On Thursday, Iran’s Supreme Leader Ayatollah Ali Khamenei warned that the United States was sure to “suffer loss” if it took military action in Syria, adding that Washington was using the reported chemical weapons attack near Damascus on August 21 as a pretext for intervention. The Syrian regime has denied using chemical weapons, calling US claims “blatant lies.”

Iran has remained a staunch ally of the regime and has actively helped Syrian troops loyal to Assad on the battlefield. The Iranian-backed Hezbollah has also been an active player on the side of Assad in the civil war that has raged in the country for two-and-a-half years, claiming the lives of over 100,000 people, according to the latest UN figures.