The Wall Street Journal (and NASA in an April 2014 report) recently touted America’s “serious” response to the threat of near Earth asteroids, but the only concrete action seemed to be, “The warhead components, containing highly enriched uranium, are being retained ‘pending a senior-level government evaluation of their use in planetary defense against earthbound asteroids.'”
Fortunately they’re exploring other options because nuking an in-bound asteroid is more apt to MRV the asteroid as destroy it. As noted in the Wikipedia article, a pattern of warheads have the potential of greater damage that a single, larger warhead. Not that we should just let the asteroids come.
The WSJ article mentions exploring other options, such as space tugs and impactors. Impactors still have the MRV potential. Space tugs so far only exist on the sets of science fiction movies.
Given that asteroid impacts may have caused several pre-historic die-offs, it’s probably appropriate to be looking for options to detect and deflect–if not destroy–potential Earth impactors.