I'm not an Egypt watcher, but it appears the Muslim Brotherhood is continuing plans to isolate the Arabian Peninsula. Iran's move to seal the western approaches didn't pan out thanks to both Bush '41 (Somalia operation) and Bush '43 (US, France, and initially Germany in Djibouti). The MB's real objective, in my opinion, is closing the Suez Canal. This, with Iranian control of the Strait of Hormuz, will effectively put our economy in bottom of the tank thanks to Obama's prior spending sprees.
Our capability to militarily act is extremely limited, even if the administration had the will to do so -- which it doesn't. In 1956, France and Britain occupied the canal zone ostensibly as part of establishing a buffer between Egyptian and Israeli forces during the 1956 War. The Eisenhower administration criticized this move since they viewed it as former colonial powers trying to regain their possessions. However, if they hadn't done this, commerce and oil would have certainly suffered with grave effects in Europe. Ike and the US could afford to take the high ground since at the time we had no qualms about pumping our own oil.
We are now in a similar situation, but instead of a Nasser-led nationalist movement, we are facing a violent Islamist MB which would have no problem in shutting down the canal to the infidels, and I would imagine the military chiefs would balk at any type of operation given their soft apporach to warfare. Frank Gaffney sums it up nicely here.