These early tests are always declared to work FSVO "working".
Note it fired a "test laser" and instruments on the missile indicated the laser had a "hit". So they didn't actually disable/destroy the missile - basically it was a computer controlled Lazer Tag setup.
They did, in fact, destroy the missile. The articles about this event are badly worded. From the original MDA Press Release:
At 8:44 p.m. (PST), February 11, 2010, a short-range threat-representative ballistic missile was launched from an at-sea mobile launch platform. Within seconds, the ALTB used onboard sensors to detect the boosting missile and used a low-energy laser to track the target. The ALTB then fired a second low-energy laser to measure and compensate for atmospheric disturbance. Finally, the ALTB fired its megawatt-class High Energy Laser, heating the boosting ballistic missile to critical structural failure. The entire engagement occurred within two minutes of the target missile launch, while its rocket motors were still thrusting.
However, the fact that they were able to do it from the ALTB during the boost phase of the missile launch (first two minutes!) is worthless. To do this during an actual ICBM attack would require /many/ ALTBs to be flying over enemy territory at the time of launch. This is because of simple physics. The earth is round. ICBM launches take place on the other side of the earth. The ICBM will no longer be in the super vulnerable boost phase when we can target them with the ALTB platform.
The immediate reaction is that satellites would solve this problem.
But, there are two problems with that idea. First, to make a laser powerful enough to destroy/disable an ICBM requires a lot of space (there's a reason they use a 747 and it's not sex appeal). Satellites just aren't big enough or powerful enough or reliable enough to be effective platforms.... and we'd need /a lot/ of satellites. Second, there are treaties about weapons in space that no one wants to break. Modern society (particularly the United States) are too heavily invested in delicate satellites for communications, commerce, etc. Once weapons are allowed up there... back to the industrial era we go.
It's not tactically worthless. You don't have to dig any deeper than the wikipedia article to learn about its mission:
The ABL was designed for use against tactical ballistic missiles (TBMs). These have a shorter range and fly more slowly than ICBMs. The MDA has recently suggested the ABL might be used against ICBMs during their boost phase. This could require much longer flights to get in position, and might not be possible without flying over hostile territory. Liquid-fueled ICBMs, which have thinner skins, and remain in boost phase longer than TBMs, might be easier to destroy.
If the ABL achieves its design goals, it could destroy liquid-fueled ICBMs up to 600 km away. Tougher solid-fueled ICBM destruction range would likely be limited to 300 km, too short to be useful in many scenarios, according to a 2003 report by the American Physical Society on National Missile Defense.
Upshot being, homeland defense in general, and ICBMs in particular, are not really its mission. It's designed to counter TBMs--that is, artillery. Potentially very long range artillery, but still.
Being able to shoot down artillery from the air with a lot of speed and flexibility could be useful in any number of scenarios. Probably not homeland defense, though. Oceans and all.
Against Russia or China, this kind of a system is worthless. I believe that the contractor is selling this as deterrent against Iran or North Korea.
... And even then it's worthless, because if either wanted to nuke the US, they wouldn't launch it on a missile, they'd pack it on a ship and sail it to New York.
From a certain perspective, it is actually good that this is worthless against China or Russia: namely, if they don't perceive it as a threat, then they won't fight its deployment or try to build up arms in response.
Consequently, it may prove useful in neutralizing the threat posed by medium-to-long-range weapons possessed by particular actors (Iran, North Korea) to allies in the region. (I say allies because I agree with you - if they wanted to attack the US, doing so via conventional means would be extraordinarily foolish.)
Note it fired a "test laser" and instruments on the missile indicated the laser had a "hit". So they didn't actually disable/destroy the missile - basically it was a computer controlled Lazer Tag setup.
Mission accomplished = more funding.