Israeli diplomats have told their American counterparts that Israel would be prepared to take military action to save the Hashemite Kingdom of Jordan if it came under attack by jihadist militants, the Daily Beast reported on Saturday.

The threat posed to Jordan by the Islamic State of Iraq and Syria (ISIS) which has already taken over wide swathes of Iraq and Syria, is of deep concern to the Obama administration and was the subject of a confidential briefing by administration officials to senators last week, according to the online news site.

The chief concern is that an attack on Jordan would inevitably drag Israel and possibly the United States into the fighting.

“Jordan could not repel a full assault from ISIS on its own at this point,” one senator was quoted as saying. Jordan "will ask Israel and the United States for as much help as they can get.”

The Daily Beast quoted Thomas Sanderson, co-director for transnational threats at the Center for Strategic and International Studies, as saying that both Israel and the U.S. view the survival of the Jordanian monarchy as a paramount national security objective.

“I think Israel and the United States would identify a substantial threat to Jordan as a threat to themselves and would offer all appropriate assets to the Jordanians,” he said.

“It’s impossible to rule out boots on the ground from Israel or the United States, but that is the least likely scenario. Amman would have to be under siege for that to happen,” he said.

In the first signs of pro-ISIS sentiment in Jordan, demonstrators in the desert city of Maan unfurled the black battle flags of the al-Qaeda-inspired extremist group on Friday and shouted anti-government slogans, the Washington Post reported.

“Down, down with Abdullah,” the demonstrators shouted, referring to King Abdullah II, a close U.S. ally, who is widely viewed as a moderate in a country considered an oasis of stability in the Middle East.

Abdullah’s government has put the country’s Border Guard on alert, following the ISIS surge in Iraq. Troops along Jordan's 125-mile frontier with Iraq have been reinforced with additional tanks and armor to thwart any move into Jordan by the ISIS militants.

Dana Daoud, a spokeswoman for the Jordanian embassy in Washington, was quoted by the Daily Beast as saying that the country’s military and security forces were fully capable of meeting the ISIS threat.

“We are in full control of our borders and our Jordanian Armed Forces are being very vigilant,” she said. “We have taken all the precautionary measures. So far, we have not detected any abnormal movement. However, if anything threatens our security or gets near our borders it will face the full strength of our Jordanian Armed Forces.”

Jordan is a close ally of the U.S. and one of only two Arab countries (the other being Egypt) living in formal peace with Israel. After U.S. forces lost access to Iraqi military bases in 2011, Jordan emerged as the most important base for the CIA in the region. Moderate Syrian rebels are currently being trained by the CIA from bases inside Jordan.

On Thursday, the White House asked Congress to authorize an additional $500 million for military training and equipment for those opposition forces.