A senior Israeli official has voiced concern for Jordan’s future stability given encroaching Islamist-led insurgencies in the region, a departure from Israel’s customary reticence about its neighbour and security partner.

Jordan, one of two Arab countries to have signed peace treaties with Israel, has largely weathered the upheaval in much of the Middle East over the past five years. It has low-key military backing from the United States and Israel.

“There is a stable regime in Jordan, which is dealing with dramatic challenges,” Amos Gilad, senior regional adviser to Israeli Defence Minister Moshe Yaalon, said in an interview with the Israel Defense journal.

But while Israeli officials generally limit themselves in public to extolling Amman’s conduct, Gilad noted the big influx to Jordan of refugees from next-door Syria and Iraq, where Islamic State insurgents have set up fiefdoms.

“There is no doubt that ISIS is trying to penetrate (Jordan) from there, on a small scale for now,” he said.

“So they have worries. We should also be worried, but there is no way of not being impressed by their capabilities, military and otherwise.” In Washington on Monday, U.S. Defense Secretary Ash Carter met Jordan’s King Abdullah and discussed what a Pentagon spokesman described in a statement as “mutual concerns in the region, including the ongoing crisis in Syria”.