(CNSNews.com) – Defense Secretary James Mattis on Thursday told Congress he can imagine that escalating tensions between Israel and Iran and their proxies in Syria could escalate into something much bigger.

In February, Israeli jets struck a Syrian airbase from which an Iranian drone, loaded with explosives, flew into Israeli airspace. The Israelis shot it down.

Sen. Jack Reid (D-R.I.) asked Mattis, “Is there a significant risk of escalation at this moment that would not only engulf Syria but spread throughout the region?”

“A complex question,” Mattis responded. “I believe the short answer is yes, Senator. I can — I can see how it might start. I’m not sure when or where.

“I think that it’s very likely in Syria, because Iran continues to do its proxy work there through Lebanese Hezbollah and over into Lebanon. And so I can imagine this sparking something larger.”

Sen. Reid noted that anti-Assad rebels still control the southern border of Syria, near Jordan. He asked Mattis what Jordan and Israel might do if Assad and his allies gain control of that area:

“Assad’s continued presence and his forces’ presence, sir, in light of what they’ve done over several years to their own people, and then when you look at them hosting Lebanese Hezbollah — any kind of position like that along the southern border is a direct threat against Jordan, against Israel,” Mattis replied.

“And it’s something we’re going to have to address. We’re trying to do that through the diplomatic proess, the U.N. process, referred to as the Geneva process, but to date, that has not been availing.”

Mattis was testifying before the Senate Armed Services Committee on April 26, 2018.