Chechen guerillas are using new, cruder tactics against Russian helicopter gunships, stretching ropes across gorges considered as possible routes for helicopters. The desired results are, after colliding with those ropes, the helicopter might lose stability and crash. 

The rebel leadership has placed a cash bounty on helicopters and their crews, so there is a strong financial incentive to actually engage these beasts. While the rebels continue to try and track helicopters down from the ground, this may be an indicator that their supply of MANPADS has run low. They have even fired assault rifles at helicopters five times in the week prior, without effect. - Adam Geibel