As U.S. lawmakers anxiously track Egypt’s post-revolutionary struggles, they’re also following the fortunes of a little-publicized group of Americans who have found themselves caught up in Egypt’s most pressing internal security problems.

Nearly 700 U.S. soldiers are camped in the Sinai desert, making up almost half of the 12-nation Multinational Force and Observers, established in 1981 to monitor the peace treaty between Egypt and Israel. Officially, their job is to make sure Egypt abides by the treaty’s strict limits on troops and armor in a strip of the Sinai along the Israeli border. For more than three decades, they had little to report.

But with the breakdown of internal security in the Sinai since Egypt’s 2011 revolution, the lightly armed observers have been alerting Egyptian and Israeli officials about the growing presence of terrorists in the Sinai. “It’s called mission creep,” said David Schenker, an Arabist at the Washington Institute for Near East Policy who monitors the MFO.

Indeed, over the past two years, heavily armed Bedouin tribesmen and terrorists affiliated with al-Qaida have attacked and killed Egyptian and Israeli soldiers, blown up a natural gas pipeline more than a dozen times and smuggled weapons — including shoulder-held anti-aircraft missiles — across the Sinai Peninsula to Palestinian militants in the Gaza Strip. Last September, jihadists attacked the MFO base at El Gorah near the Gaza Strip, wounding four observers, destroying a vehicle and a guard tower and making off with communications equipment and ammunition, according to the Israeli daily Haaretz.

Following the incident, MFO Director General David M. Satterfield, a former U.S. diplomat, briefed lawmakers on the importance of the MFO’s missions and the growing dangers they face.

Sen. Lindsey Graham, R-S.C., said the threat to MFO peacekeepers is one of the main reasons he and other lawmakers are urging Egypt to bolster its counterterrorism capacity.

“I’m very concerned about them,” he said. “They’re sitting ducks.”