Hellfire AGM-114K is a laser guided ATGM, as well as the Mokopa
etc , quite a lot of them.
One way to counter them is by way of softkill APS with RWR + smoke
grenade, or decoys, and electro-optical signals, infrared or laser
jamming etc
To counter this countermeasure is by not lasing directly at the
target initially, but say a few metres in front of target, only
"paint' it , say the ATGM is abt to close in , so let as little
time as possible for target to activate it's countermeasure.
Spike is optically guided by fibre optics as well as by TI, to
counter perhaps softkill APS with RWR + smoke grenade, but there is
very little reaction time , making it worse by the loft trajectory
of a top attack ATGM.
Therefore softkill APS will be quite difficult counter modern ATGM,
Hardkill APS with MW radar plus some kind projectile to intercept
incoming ATGM.
Read abt APS from here:
http://www.defense-update.com/features/du-1-04/soft-kill-intro.htm