There's a little funding to search for hazardous asteroids. JPL has a growing data base of known near earth asteroids. We're doing a good job of finding the Chicxulub sized rocks. Rocks big enough for extinction level events are easy to see.
While we may have a good inventory of dino killers, potential city killers are another matter. Tunguska sized rocks are much harder to see. The vast majority of these rocks are probably still undiscovered. And the Tunguska or Chelyabinsk sized rocks are probably a million times more common than the Chicxulub sized rocks. To find these smaller rocks we may need orbital telescopes devoted to the search.
I hope to see the Asteroid Redirect Mission ARM funded. This mission calls for parking a small asteroid (5 to 7 meters) in lunar orbit. The proposed retrieval vehicle would be SEP (solar election propulsion) as described in the Keck Report. Such a vehicle would be too small to deflect a Chicxulub sized rock. But it might be able to deflect a city killer.
The co-authors of the Keck report include John S. Lewis, Chris Lewicki, Don Yeomans, as well as other well known scientists and engineers who study asteroids. Many of the co-authors are now part of Planetary Resources or Deep Space Industries, two companies that hope to mine asteroids for profit.
Deflecting larger asteroids would require space infrastructure. Our elected representatives are too ignorant and short sighted to fund it. But if mining space resources could return a profit, infrastructure would naturally grow. That is why I see Planetary Resources or Deep Space Industries as the best bets for planetary defense.