U.S. Secretary of State Rex Tillerson on Friday warned other countries and groups against using Lebanon as vehicle for a larger proxy fight in the Middle East, saying the United States strongly backed Lebanon’s independence.

Tillerson said he recognized Saad al-Hariri as Lebanon’s prime minister and called him a “strong partner of the United States.”

Hariri unexpectedly resigned his post at the weekend from the Saudi Arabian capital of Riyadh and accused Iran and its Lebanese ally Hezbollah of sowing strife in the Arab world. His resignation thrust Lebanon into the front line of a regional competition between Sunni Saudi Arabia and Shi‘ite Iran that has also buffeted Syria, Iraq, Yemen and Bahrain.

Tillerson’s backing of Hariri and the Lebanese government contrasted sharply with the approach taken by U.S. ally Saudi Arabia which has lumped Lebanon with Hezbollah as parties hostile to it. “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,” Tillerson said in a statement, as reported by Reuters.

Lebanese authorities have said Hariri is being held against his will in Saudi Arabia, a charge that Riyadh has denied. Tillerson earlier said there was no indication Hariri was being held in Saudi Arabia against his will but that Washington was monitoring the situation.

Tillerson’s statement said there was no legitimate role in Lebanon for any “foreign forces, militias or armed elements” – an apparent reference to Hezbollah and its regional backer, Iran. But Tillerson also cautioned 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.”