As the UAE offers its condolences to Saudi Arabia on the death of King Fahd with seven days of official mourning, this mark of deference and diplomacy will not have been lost on the new Saudi ruler, Abdullah. While relations between the two countries are complex, having their roots in tribal rivalries that have erupted even in living memory, essentially common interests, similar threats and shared experiences have forged a close bond over the years.
Saudi expansionism and resentment of Britain's influence in the Gulf tainted relations between the kingdom and its smaller neighbours during the period from the 1930s to the 1970s. In the power vacuum that followed Britain's withdrawal from the Gulf in 1971, the weaker regional states were obliged to accept Saudi protection.
Despite some border disputes between the states of the Arabian Peninsula themselves, Saudi Arabia played its role as guardian diligently as regards external threats. In 1981 it led the way to the establishment of the Gulf Cooperation Council (GCC) in direct response to the Iran-Iraq war. Ten years later, Saudi Arabia was quick to come to Kuwait's aid after the Iraqi invasion. Yet King Fahd's decision to allow Western troops onto Saudi soil to liberate and then protect Kuwait is one for which the Saudi rulers are still paying a domestic political price today.
Initially stimulated by defence considerations among the six states of the Arabian Peninsula - Bahrain, Kuwait, Oman, Saudi Arabia, Qatar and the UAE - the GCC has evolved over the years into more of an economic zone than a political one, and as the organisation approaches its 25th year, co-operation in defence issues considerably lags behind those of trade. A customs union was established in 2003 ahead of planned full monetary integration in 2010, but despite a defence agreement signed in Bahrain in 2000, military co-operation between the states remains minimal.
While economic co-operation will benefit all the people of the Arabian Peninsula, most analysts agree the principal reason for lack of progress on more political issues is residual suspicion of Saudi motives and resentment of the kingdom's dominance of the GCC. For the southern Arabian states - Oman, Qatar and the UAE - Saudi expansionism and territorial incursions sit within living memory.
In the case of the UAE, and Abu Dhabi in particular, the Buraimi crisis, finally resolved with British military help in 1955, remains particularly prominent in the national consciousness. Saudi Arabia only dropped its claim to the important Buraimi oasis in 1974 in return for territory in the west of the emirate. In fact, Saudi Arabia voted against UN membership for Qatar and Oman as late as 1972, and refused to recognise the newly formed UAE until the 1974 territorial agreement with Abu Dhabi was signed.
As US involvement in the Gulf became more direct after the 1990-91 Gulf War, reliance on Saudi Arabia diminished. And as the UAE's prudent economic and oil policies have borne fruit, the Emirates have found they carry far more weight in the region than previously. Along with Oman and Qatar, the UAE has been finding that in a globalised world, decisions no longer need to be taken in Riyadh. Throughout 2005, the cosy co-operation of the other Gulf states has often appeared in defiance of Saudi interests.
GCC tensions have been particularly obvious over the question of bilateral free trade agreements with the US, which Saudi Arabia feels violate the GCC customs union. However, despite Saudi protests after Bahrain signed its agreement in 2004, all the other GCC partners have pursued talks with the US, and Riyadh has been forced to back down.
The Saudis have also been upset at proposals to build a causeway linking Bahrain to Qatar and another between Qatar and the UAE that will reduce Saudi Arabia's territorial relevance to these states.
The causeway issue touches on a long-standing border dispute between the UAE and Saudi Arabia which resurfaced not long after Sheikh Khalifa came to power. A 1974 agreement gave Saudi Arabia a corridor to the sea between Qatar and the UAE, and it is off the coast of this that the UAE-Qatar causeway will likely run - through what Saudi Arabia sees as its territorial waters. Yet the 1974 agreement was never ratified by the UAE, which felt Sheikh Zayed had signed it under duress, despite an amendment in its favour in 1993. Thus the Emirates are reluctant to recognise any Saudi sovereignty over the strip and its waters.
At the same time, it is even possible that the massive Dolphin gas pipeline project would also cross, if not Saudi waters themselves, then the exclusive economic zone beyond, which is reserved for Saudi use under maritime law.
Initially it was assumed that the resurfacing of disputes over this strip, shortly after Sheikh Khalifa took over from his father, had been instigated by Saudi Arabia, which wanted to test the new ruler. But most reports suggest Sheikh Khalifa stood his ground, and might himself have brought up the dormant grievance in his visit to Riyadh in December 2004.
Ultimately, the dispute is no major threat to regional stability, most analysts argue, but merely some muscle flexing in the face of new geo-political realities. At this stage both sides are showing their first negotiating hand, but compromise can be expected in the future. The Gulf states share much in common in the religious, cultural, economic and political fields. In the final analysis, the Gulf states will continue to share an interest in each other's internal and external security, and despite the volatility of the region, hot and cold air blown between one state and another is as unlikely to come to anything in the near future as fishing disputes between the UK and Spain.
This is the clear message as the UAE joins in mourning the late Saudi Arabian king, setting aside recent tensions to send a clear message of unity and brotherhood.