Ever since the United States and Saudi Arabia fell into something of an alliance in the late 1970s, the world's most unlikely partnership has had lots of down moments.

Another big one came last weekend, when Saudi intelligence chief Bandar Bin Sultan al-Saud told European diplomats that his country would step back from cooperating with the United States on Syria, according to the Wall Street Journal and Reuters. Bandar said his country's recent decision to refuse a seat at the U.N. Security Council was meant as a show of public protest against the United States, its long-time ally.

This very public Saudi jab at the U.S. is the latest in a series of increasingly frequent disputes between the longtime allies. They are probably not on the verge of breaking up, as observers have been predicting since 1990, when the kingdom was roiled by popular outrage against the alliance. But many of the mutual interests that have brought the two countries together seem to be falling apart.