The US and the United Arab Emirates (UAE) discussed the possibility of lifting sanctions on Syrian President Bashar Al-Assad if he peels himself away from Iran and cuts off weapons routes to Lebanon’s Hezbollah, five people familiar with the matter said according to Reuters.

The discussions took place before anti-Assad rebels swept into Aleppo last week in their biggest offensive in Syria for years.

According to the sources, the new rebel advance is a signal of precisely the sort of weakness in Assad’s alliance with Iran that the Emirati and US initiative aims to exploit. But if Al-Assad embraces Iranian help for a counter-offensive, that could also complicate efforts to drive a wedge between them, the sources said.