gCaptain reports that an Egyptian Coast Guard vessel has been attacked by a militant group, Egypt’s Islamic State affiliate, “Sinai Province.”
Other reports identified the vessel as a frigate, and the weapon as a guided missile. It does appear that the vessel is smaller and the missile was probably an anti-tank weapon rather than an anti-ship cruise missile.
Reportedly the vessel had been engaging elements ashore.
This is the type of extemporaneous weaponry the Coast Guard could expect a terrorist organization to use against the USCG if they attacked the US. We should be particularly concerned that they not be able to target specific critical systems on our cutters. Currently I consider 4000 yards to be a reasonable standoff distance to minimize this possibility.
Chuck Hill's CG Blog 
Depends on which missile was used and where they got it?
Standing off 4,000 yards are more does not guarantee they could not hit the cutter, but it makes it far less likely that they could target specific components, like the gun, that would make it impossible for the cutter to hit back.
We need weapons that are effective to at least that range.
Probably some good guesses here about both the target and the weapon.
http://www.informationdissemination.net/2015/07/the-islamic-state-at-sea.html
He thinks the target was one of these 26 meter Swiftships PBs.
http://www.swiftships.com/military-vessels-specifications/26-meter-patrol-boat/