Busting it up so that it burns up high in the atmosphere, rather than causing damage on the ground, is almost as good as deflecting it.
One important bit of data is how “solid” these asteroids are, in the sense of how much impact it takes to bust them up.
Chances are, the only way to find out how solid they are is to smack ‘em with something and see what happens. Teller suggested a large number of bullet-shaped tungsten objects, embedded in a sort of net. It would be launched wadded up, then deployed opened up wide, and sent head-on into the interloper rock. Most of the energy to slice-and-dice would be from the rock itself.