Can an incoming intercontinental ballistic missile be destroyed by an

Can an incoming intercontinental ballistic missile be destroyed by an intense laser beam? A beam of intensity 108 W/m2 would probably burn into and destroy a non-spinning missile in 1 s.
(a) If the laser had 5.0 MW power, 3.0 mm wavelength, and a 4.0 m beam diameter (a very powerful laser indeed), would it destroy a missile at a distance of 3000 km?
(b) If the wavelength could be changed, what maximum value would work? Use the equation for the central diffraction maximum as given by Eq. 36-12 (sin θ = 1.22λ/d).