Saudi Arabia’s foreign minister says that Syrian President Bashar Assad has two choices: “either to leave through negotiations” or be forcibly removed from power.

Foreign Minister Adel Al-Jubeir spoke Thursday to reporters during a two-day meeting of Syrian opposition groups taking place in the Saudi capital, Riyadh. The talks are aimed at forming a unified front ahead of proposed peace talks with Assad’s government.

Al-Jubeir says he hopes the Syrian opposition can come up with a common vision for Syria during the meeting. He urged delegates to prove wrong those who argue that the Syrian opposition is too fragmented to present a unified front at future peace talks.

Saudi Arabia has been a key backer of Sunni opposition blocs pushing for Assad’s ouster.