The "secondary" use for space debris mitigation is actually much more important than honing survival skills for asteroids: when you can deal with space junk, asteroids - if any dangerous show up - will come naturally.
If something is not done with space debris FAST the space may be lost for generations.(Then they would have to figure out some ground based laser solution to clear up the skies bit by bit).
Finally somebody comes with an idea that sounds practical to me. There is no novelty to blast the junk with lasers - any true and tried Star Wars fan can imagine that (even I did in one of old Gizmag comments on the topic) - but SWARMS of laser-wielding satellites hired for clean up job IS impressive.

Space weapons - what a terrific idea! What could possibly go wrong?!

I'm with you Grunchy. Chinese, Russians, Iranians ... will love this, nothing like laser equipted satellites to evoke action from the perenially paranoid.

re; Grunchy
They are not weapons but While they could be used as weapons against objects in space the way that Laser beams spread mean that the beam would have defused to much to harm ground objects. At least three countries already have anti-satellite weapons any way. ..............................................................................................................................
First. It does not matter how radioactive you leave the object if it misses earth. Second. The farther away the object is when you apply the force the less velocity change you need to impart to generate a miss. In the Armageddon scenario they should have just thrown as many nukes as soon as they could. Preferably in ground penetrating casings so as much of the energy as possible goes into generating the miss. In the Deep Impact scenario one full yield (100 megatons) Tzar Bomb (AN602 hydrogen bomb) if they launched the rocket within weeks of discovery. I would launch as many bombs as I have heavy lift rockets on hand.

I always thought the best way to use an H-bomb to deflect an asteroid would be off to the side, giving it a push without making a debris cloud.
As for the laser swarms and space debris, my idea is even cheaper. Put huge blocks of aerogel in retrograde orbits. Tiny and large objects would lodge in it, be trapped, and slow the block and de-orbit it to burn up with all the chips and chunks.

We know for certain that there is going to come a time when an asteroid will appear that is on course to strike the earth. It might show up on our radar thousands of years off, or it could be tomorrow, but show up it will at some time, so the sooner we have in place a defence mechanism, the better it will be for the planet.
As for space weapons, I cannot see what the concern is. No rogue nation is going to fire lasers from space down to earth for two reasons. First, as the unattributed comment above points out, the beam will be diffused by the atomosphere, and second, even if such an attack were possible, all satellites are of know origin, so any attack from a satellite will identify the culprit nation and thus make it liable to retalliation.
If a rogue nation wants to nuke the US, it will do it by sailing a merchantman or yacht into the port of New York, say, with the device secreted in the hull somehow. While there would be suspicions as to its origin, who could beat a defence that claimed it must have been attached to the vessel by some terrorists when it was in its last port of call, which might have been in some completely neutral nation? Another route would be across the Canadian border. Some people I know even crossed it by mistake in the backwoods somewhere and were amazed to come across another crossing point, this time marked, that told them they were about to leave the U.S.A. when as far as they knew, they had not even entered it.

The Earth should be surrounded by Hubbles looking for asteroids, et al..

re; Brian Hall
Most of the debris generated by the detonation of an impact fused or ground penetrating warhead would receive enough acceleration that they would miss the earth on the other side. More importantly all the matter thrown out of the crater is the reaction mass in a very short lived rocket engine burn and therefor accelerates the large piece to a far greater extent than the near miss detonation approach. If the low probability event happens that some highly radio active 100m sized pieces (or just thousands of tons of dust) do get put an a course that still impacts earth it is a small price to pay for avoiding the extinction event. Also bear in mind that the smaller pieces can be further busted up before entering the atmosphere by normal ICBMs and the radio active dust will be spread widely enough to make it essentially harmless. If the deflection can be made by more gently applied force good but in the case of a dinosaur killer the deflection must be made. ............................................................................................................................
re; funglestrumpet
If you separate your thoughts with a line of periods your comment is still attributed at the bottom of your comments.

re; Christoffer Thor Wang Sperling First. You are confusing Einstein's and Newton's work. E=mc2 means that a tiny amount of matter converts to vast quantities of energy. It is Newton's Laws of Motion that include every action has an equal and opposite reaction.
Second. There is a matter of scale a hundred car coal train moving a 100MPH is by several thousand orders of magnitude more effected by running into a single mosquito than the earth is by all the rockets we have sent out of orbit. The Tunguska event alone had more effect than all the rockets ever launched.

The Armaggedon asteroid is predicted to be 1 mile in diameter. It will cause Atlantis to rise . others to sink. My interpretation is may/june 2016