Defense Secretary Chuck Hagel says that US forces are "ready to go" if the administration decides to strike against alleged Syrian chemical weapon use. As Bloomberg notes in the infographic below, US Navy guided missile destroyers in the Mediterranean Sea are within range of Syrian targets.. and the ships have a combined inventory of more than 200 cruise missiles.
On the other side, the Syrian Air Defense system is very robust, and as Stratfor notes, with an estimated 54,000 personnel, Syria's air defense network is twice the size of former Libyan leader Moammar Gadhafi's air force. Here is the Syrian theater of operations...
The bulk of Syria's SAM weaponry is composed of the SA-2, SA-3, SA-5, SA-6 and SA-8 SAM systems, which were also operated by Gadhafi's forces. However, the Syrians operate these systems in far greater numbers, have devoted significant resources to maintaining and upgrading these missile batteries and have also successfully deployed their SAM systems in a dense and overlapping layout that would complicate operations to suppress enemy air defenses.
Though also a Russian ally, Gadhafi did not have the more advanced Russian air defense systems that the al Assad regime possesses. For example, Iran reportedly financed Syria's acquisition of 50 SA-22 systems first delivered in 2007 -- 10 of which allegedly ended up in Iranian hands. The Syrians are also thought to operate several SA-11 systems, which the Libyans did not have. Syria's defenses against an air campaign are not restricted to the ground. Its air force can contribute dozens of fighter aircraft and interceptors, which any intervention force would also have to contend with.