The heavily doctored video appears to show a jihadi firing a rocket at a naval patrol ship in the Mediterranean sea, causing it to burst into flames.
Footage of attack on the ship first emerged in July after the Egyptian military said a coastguard vessel had exchanged shots with militants just two miles off the coast of northern Sinai, an area bordering Israel and the Gaza strip.
The military said it suffered no casualties although it is understood several patrol workers suffered minor burn injuries.
The video also appeared to show militants laden with weapons and ammunition apparently targeting victims and causing explosions on roads and in built-up areas.
It comes after the security at a number of popular tourist resorts in Egypt was increased following an attack by ISIS militants on a town just a few hours away.
Extra armed guards were drafted to Sharm El Sheikh and Hurghada after 50 Egyptian government troops were slaughtered in the Sinai province, a peninsula popular with British holidaymakers.
Full article: Ominous warning as ISIS reveal arsenal of weapons at disposal of Egyptian supporters (Express)