"We have had a long relationship with Egypt and the Egyptian people and it would not be wise to abruptly change our assistance programme.. ..The smart policy is to review this matter...There is not a simple or easy answer here"- Jay Carney, US spokesman.The US is clearly hamstrung on the military takeover ( i.e coup ) because it cannot be seen to be be backing the army against the Egyptian Muslim Brotherhood when it is backing the Sunni insurgents in their struggle against President Assad's Alawi Shia regime in Syria.
In Syria the Muslim Brotherhood has been a major component of the armed opposition to Assad backed by Turkey, a NATO nation, and the removal of Morsi has deprived them of one of its most significant backers and ideological support from its original homeland.
It would be absurd for the US to openly back the army takeover as its erstwhile enemy Assad has claimed "What is happening in Egypt is the fall of what is known as political Islam..whoever uses religion for political aims, or to benefit some and not others, will fall".
Despite the predictable claims that the CIA just must have been behind the coup ( without any evidence ) there was absolutely no interest the US could have had in either backing one or even being seen to back on. It has taken the US by surprise and it has no idea how to react.
In fact, only Tony Blair has openly criticised the Muslim Brotherhood and advocated working with the new government, something that clearly has more to do with his obsession with the idea that 'inactivity' is a policy choice with consequences too ( mostly due to his role in the invasion of Iraq ).
The US is probably hoping that the killing of 51 Muslim Brotherhood supporters cannot lead to a reaction strong enough to pose serious resistance to the military's position in Egypt which it secures through its funding. If some radicals resort to terrorism, then the US can justify that subsidy.
If, however, if the calls by the Muslim Brotherhood leaders to 'rise up' go beyond street protest, leading to further provocations and heavy handed military responses, the potential for serious civil conflict will grow and this is bound to call into question the wisdom of giving arms to the Syrian insurgents.