Saudi Arabia's Crown Prince Mohammed bin Salman arrived in Abu Dhabi on an official visit on Tuesday, as part of a tour of the Gulf states ahead of next week's GCC summit. Prince Mohammed's trip began on Monday in Oman, where he met with Sultan Haitham bin Tarek to discuss a series of issues of mutual importance to Saudis and Omanis, from regional security to economic development. Similar topics were addressed during the UAE leg of the tour, during meetings with Sheikh Mohamed bin Zayed, Crown Prince of Abu Dhabi and Deputy Supreme Commander of the UAE Armed Forces. Prince Mohammed's visits, as well as the GCC summit that will soon follow, are important reminders of the region's interconnectedness, and the desire of its leaders to maintain a sense of unity. The wide range of the discussions held so far reflected the equally wide range of challenges – and opportunities – that lie before the Gulf as the year draws to a close. In Muscat, the Saudi and Omani leaders agreed to establish a joint council to promote economic development between the two countries, and inaugurated a motorway linking them through the region's Empty Quarter. The motorway is significant because it is the first road link between the two neighbours, making it not only an economic game changer for its freight transportation potential, but also a wider symbol of the progress being made in consolidating regional economic integration. Further integration is a fundamental part of regional stability, which was a key theme of the Prince's visit to Abu Dhabi. Saudi Arabia and the UAE have both taken steps to diversify their economies, and boost their economic strength and competitiveness over the past year, and the regional benefits of stronger, more open markets in the two countries will not be lost on the region's governments. Relations between Saudi Arabia and the UAE, Sheikh Mohamed emphasised, "are founded on fraternity, history, geography and common interests". A sense of fraternity is particularly important in light of the challenges facing the world, from tackling the pandemic to climate change, in addition to security concerns that have heightened in recent years. On the eve of Prince Mohammed's tour, Saudi air defences intercepted two weaponised drones, and destroyed a ballistic missile launched towards the capital Riyadh on Monday. The attacks were carried out by the Houthi rebel group in Yemen, which overthrew Yemen's internationally recognised government in 2014. The Houthis have long been sponsored by Iran, and this week's attacks – simply the latest in a barrage against Saudi cities throughout the past year – bring to the spotlight some of the regional security concerns that will form the focus of the upcoming GCC summit. Another is Iran's interference in other parts of the Arab world, as well as the country's nuclear ambitions. It is a difficult challenge to overcome, but as many of the Gulf's diplomats have emphasised repeatedly in recent months, the guiding principle in any effort to overcome it is the desire for a peaceful and prosperous relationship with Iran that puts mutual interests first. That prioritisation of common purpose is a principle that has held for many years in the Gulf. And as the most recent flurry of economic and diplomatic activity that comes with Prince Mohammed's tour shows, it is one that the region's leaders intend to carry into the future.