Leaders of the Gulf Cooperation Council (GCC) countries kicked off summit talks in Saudi capital Riyadh on Sunday.
The talks come one day after U.S. President Donald Trump arrived in Saudi Arabia for his first presidential trip abroad.
Saudi Crown Prince Mohamed bin Nayef chairs the meeting, which is also attended by the leaders of Qatar, Kuwait, Bahrain, the Crown Prince of Abu Dhabi and Oman's deputy prime minister.
Following the GCC summit, Gulf and Muslim leaders will hold summit talks with Trump with a view to bolstering cooperation between the two sides in the fight against terrorism.
On the first day of Trump's visit, Washington and Riyadh agreed on an arms deal worth almost $110 billion "to support Saudi Arabia's defense needs, according to the U.S. State Department.
Turkey's Foreign Minister Mevlüt Çavuşoğlu also arrived in Riyadh on Sunday to represent Turkey in the summit.