Doug Richardson, the editor of Jane's Missiles and Rockets, said it might have    been a Standard interceptor, the anti-missile weapon which is fitted to the    US Navy's Aegis guided-missile cruisers as part of the American missile    defence programme. 
  He said: "It's a solid propellant missile, you can tell from the efflux    [smoke] but they're not showing enough of the tape to show whether it's    staging [jettisoning its sections]." 
  Robert Ellsworth, the former US Deputy Secretary of Defense, said it was    "pretty big" but "not a Tomahawk" cruise missile.