DUBAI, United Arab Emirates - In Washington last week, arms regulators announced that Saudi Arabia is seeking $6.8 billion in advanced missiles and other equipment in its latest military buying spree. Days later, Saudi officials snubbed a seat on the U.N. Security Council in a stunning protest mostly aimed at U.S. policies in the Middle East. This role of being an eager customer and emboldened critic may come to define the new relationship between Saudi Arabia and its longtime ally: The kingdom warns it won't sit idly as Washington's views increasingly drift away from the Gulf state's priorities of keeping Iran and the West as far apart as possible and steadily supplying arms and aid to Syria's rebels. The Saudi-U.S. alliance has been among the bedrock elements of Middle East affairs for decades, and even small fissures carry outsized significance in a region that is in huge flux amid the chaotic Arab Spring fallout, the Syrian civil war and the election in Iran of moderate-leaning President Hassan Rouhani. But there is very little chance that Saudi Arabia and its Gulf partners will push their grievances against Washington far enough to risk any deep damage, knowing they need the U.S. as a source of protection, arms and international standing. Still, the script of Saudi Arabia enjoying predictable U.S. support has been rewritten somewhat after a series of high-profile breaks, including America pulling back from possible military strikes against the forces of Syrian President Bashar Assad and last month's historic U.S. outreach to Iran.