Saudi Crown Prince Mohamed bin Salman embraces Qatari Emir Tamim upon arrival in Al-Ula, Saudi Arabia for Gulf summit.

Gulf leaders are meeting in Saudi Arabia for their annual summit on Tuesday amid a breakthrough in the long-running dispute between a Saudi-led bloc and Qatar.

Saudi Arabia on Monday announced the reopening of land borders with Qatar after a three and a half-year spat that saw the kingdom, Egypt, the United Arab Emirates (UAE) and Bahrain cut diplomatic and trade ties and impose a land, sea and air blockade on the Gulf state.

The quartet accused Doha of, among other things, supporting terrorist groups and being too close to Iran, allegations that Qatar has consistently denied.

While the Saudi decision marks a major milestone towards resolving the Gulf crisis, the path to full reconciliation is far from guaranteed. The rift between Abu Dhabi and Doha has been deepest, with the UAE and Qatar at sharp ideological odds.