...and me. Though I'd say just one round, from a sniper on overwatch. Every laser beam earns something in the 30 cal range coming right back to the source.
The problem is identifying the location of the source. A laser beam is invisible unless it passes through a medium like smoke. During the Iraq war, the military developed a system for automatically returning fire (with extreme prejudice) based on locating the muzzle blast by sound. Has the military solved the problem of tracking laser fire?