The silence coming out of Washington has told the Middle East all it needs to know about President Barack Obama's attitude towards the crisis in Egypt.

Partly, it is a case of realpolitik following the blunders of the earlier Republican infatuation with regime change in Iraq, but the bottom line is that the White House has no intention of interfering in the affairs of one of its closest allies in the region.

If any further proof were needed, it arrived in the shape of four F-16 fighter aircraft promised by the US under a 1979 agreement and the promise of a further $1.55 billion in total bilateral aid next year. This includes $1.3bn in military aid and $250 million in economic aid, making Egypt a significant client and one that clearly needs to be supported.

That is the main reason for Washington's code of honour. Under US law all financial aid would have to be withdrawn if a military coup had taken place: Section 7008 of the Department of State, foreign operations, and related programmes appropriations Act of 2012 bars "any assistance to the government of any country whose duly elected head of government is deposed by military coup d'état or decree or, after the date of enactment of this Act, a coup d'état or decree in which the military plays a decisive role".

This legal code explains Washington's unwillingness to use the term in any of its pronouncements and the mildness of its diplomatic response to the ousting of President Mohammed Mursi and the arrest of his Muslim Brotherhood colleagues. The White House might not be partial to the overthrow of a democratically elected leader, but it's not terribly keen on anything that smacks of Islamic extremism either.

This diplomatic muddle is not helped by the US attitude to its other two main allies in the Middle East, Israel and Saudi Arabia, both of which are connected to what is happening and must also be placated.

Ever since the Camp David Accords, engineered by former US President Jimmy Carter in 1978, Washington has predicated its peace initiatives in the Middle East on the willingness of Israel and Egypt to co-operate and avoid the kind of confrontation that plunged the region into a series of conflicts from 1948 onwards. A contributory factor is the co-operation which the Egyptian intelligence services provide Washington in the war against al-Qaeda-inspired terrorism.

Put simply, the US knows the Egyptian Army can deliver on those issues but it's far from sure that Mursi and the Muslim Brotherhood can do the same. On the contrary, there are fears within the US State Department that some of Mursi's closest associates are not really interested in continuing the Washington nexus and feel no particular loyalty towards the idea of preventing war with Israel.

This leaves Saudi Arabia. Not only is the oil-rich nation a longstanding ally of the US but it is also an important client and regular recipient of military aid. However, its position has been complicated by recent events, especially Obama's unwillingness to become involved in the internal affairs of Egypt and Syria. Saudi diplomats fear that there could be a link between the two and that Washington's response will encourage Iran, the main Shia supporter in the region, to act more boldly in support of their co-religionists.

Ever since the civil war broke out in Syria, Saudi Arabia and Qatar have been the main supporters of the Sunni faction opposed to President Bashar al-Assad but, far from bringing the conflict to a conclusion, it has only exacerbated the violence by encouraging jihadist fighters into Syria. It has also encouraged Iran to offer more support not only to Assad but to his Hezbollah supporters.

By attempting to steer clear of this impasse, Washington is in danger of making matters much worse.

It might avoid becoming embroiled in Egyptian internal affairs because ultimately it believes that the military is the better bet, but that ostrich- like behaviour will not prevent the violence and religious hostilities from spreading across the borders of the Middle East.