k, Momentum is equal to Mass X Velocity.
using a tomahawk missile, for example, a speed of 550 mph, breaks down to 245.872 Meters per second.
The mass of said missile is: 3200 lbs, or: 1451.495 kg.
So: 1451.495*245.872==356881.9786 kg per m/s.
In this case, the change in momentum is from 356,881.9786 to 0,
So those same numbers can be used in F=MA to determine the force, so we are talking 356,881.9786 Newtons of force to stop the missile, USING ONLY ITS OWN MOMENTUM. This does not even take into account the thrust of the rocket itself which according to :http://www.astronautix.com/lvs/tomahawk.htm is another 29.4 kiloNewtons.
So overall,(in the example of the tomahawk) in a an instant, 29.4+356.881 kN of force would be necessary to stop the rocket. We are talking 386.28 KiloNewtons of force. (let me know if my physics is sketchy, its been 3 years.)
According to this handy-dandy calculator: http://www.unitconversion.org/force/kilonewtons-to-pound-forces-conversion.html
we are talking 86839.423349611 lbs of force, or over 43 tons.
Unless I've got something wrong, its an absurd feat.