Secretary of State Rex Tillerson warned Friday that Lebanon is at risk of becoming a new focus of violence as tensions rise between Saudi Arabia and Iran.

“The United States cautions against any party, within or outside Lebanon, using Lebanon as a venue for proxy conflicts or in any manner contributing to instability in that country,” Tillerson said in a Friday statement.

Saudi Arabia and Iran have traded barbs over the last week, following the resignation of Lebanese Prime Minister Saad Hariri, who blamed his departure on the threat of Iranian-linked assassins. That resignation occurred the same day that Iranian-backed fighters in Yemen fired a ballistic missile at Saudi Arabia’s capital city. Those tensions are taking place against a backdrop of concern that Iran is expanding support for Hezbollah, a terrorist group in Lebanon, in order to strengthen its position in the region.

“There is no legitimate place or role in Lebanon for any foreign forces, militias or armed elements other than the legitimate security forces of the Lebanese state – which must be recognized as the sole authority for security in Lebanon,” Tillerson said.

That’s an apparent reference to Hezbollah, which receives funding and weaponry from Iran and has played an important role in the fight to prop up Syrian President Bashar Assad. And as Iran and Hezbollah have moved forces around Lebanon and Syria, both Saudi Arabia and Israel have grown alarmed that one of their most determined enemies is gaining military strength.

“We cannot allow Lebanon to be a platform from which harm comes to Saudi Arabia. The Lebanese people are innocent,” Saudi Arabian Foreign Minister Adel Al Jubeir told CNBC on Thursday. “The Lebanese people have been dominated by Hezbollah and we need to find a way to help the Lebanese people come out from under the thumb of Hezbollah.”

Israeli officials are similarly concerned about Iran and Hezbollah’s entrenchment in Syria, a development that would allow them to threaten Jewish state from two neighboring nations.

“Israel will not allow this,” Israeli Prime Minister Benjamin Netanyahu said in October.

U.S. officials believe that Iran has given Hezbollah tens of thousands of missiles and rockets, with the goal of transferring “a GPS capability” that would allow the missiles to be guided to specific targets. "If they succeed in this, they can pick the tallest buildings in Tel Aviv, the main landmarks in Jerusalem, the airport, the ships in the harbor,” House Foreign Affairs Committee Chairman Ed Royce said in February.

That suggests that both Israel and Saudi Arabia have distinct, but related reasons to consider a conflict within Lebanon, but Tillerson warned against such action. “The United States supports the stability of Lebanon and is opposed to any actions that could threaten that stability,” Tillerson said.