Well, not really. If we're talking about the same thing, JSTARS is kind of like an AWACS for ground targets. It can see vehicles on the ground and direct others to target them, as well as relaying that info to ground commanders. TACAMO is for controlling nuclear missile subs and other strategic weapons (think mostly nukes), so that the National Command Authority (the Pres, SecDef, etc.) can maintain comm with them in the event of war.