Stardate 20031128.1556

(Captain's log): Richard writes:

I'm thinking about all the mortar and rocket attacks against positions with defended perimeters. It doesn't sound like we've got a quick and effective response to these (I mean in seconds as opposed to minutes, and not dependent on line-of-sight).

You've got a good eye for problems in physics and a good eye for tactics, so I'm hoping that we'll find out here whether this solution would be unrealistic to even test out:

I assume that incoming rounds in this size range, 50-120mm, (subsonic?) can be detected, 360 degrees, and tracked by some kind of radar unit. With some degree of reliability as to identification. The problem is like that with the Patriot antimissile system, but on a smaller scale, hence smaller time scale.

But interdiction is unrealistic, because of that smaller time scale, not to mention size of projectile.

OK, but what about response? Assume the radar unit is configured to a computer that assesses the trajectory and extrapolates a GPS position for the launch or firing point, feeds that data to a small missile with about the capability of a TOW, and fires it back along the route of the offending object, to explode on the point of origin. AP/HE with shrapnel and a marker, such as phosphorus, so that duty personnel roused by all the activity can converge on the spot and investigate.

This would have limited use if the perps are firing from crowds, schools, etc. but all the more reason to set up in the boonies, as the Marines did in Afghanistan, with good results. I feel this could be made small enough to run from a mobile unit in a convoy as well. More problems there, but perhaps response could be scaled to reduce collateral damage while still pointing to the source quickly.

The problem is that we don't want to set up in the boonies. We need those bases to be near towns or in or near cities because that's where the troops live who are operating in those towns and cities. If the base is a long way away, it means they have to travel, and it makes that travel route vulnerable.

You've also been hearing about "roadside bombs". That's what has been happening in cases where the bases are actually a long way away from where the soldiers have to go to perform their duties. And those have been causing far more casualties than mortar attacks, including many deaths among our soldiers.

So when the base is distant, roadside bombs attack the soldiers as they "commute to work" and when the bases are close, they're shelled. But when they're shelled, they're shelled from populated areas. The bases in the boonies don't get shelled because they'd rather use roadside bombs against them.

The kind of counter-battery capability Richard describes exists now. In a field-combat situation, if any of our units starts to take artillery fire, the position from which the fire came will come under our fire in just a few minutes. (I don't know the exact period, and it probably depends on circumstances anyway, but five minutes plus or minus is a decent estimate.)

Most of the larger militaries in the world have had similar capabilities for a long time, though not necessarily as rapid as ours. The tactic one uses to launch artillery fire against an enemy who has such counter-battery abilities is known as shoot-and-scoot, and it's one of the reasons why self-propelled artillery is pretty much the norm (as opposed to towed guns) for the US now. The artillery moves to a location, gets off a couple of minutes of fire, then limbers up and hauls ass before return fire starts arriving. SP guns can do that a lot faster than any other kind of heavy artillery. And it's one of the reasons why the US has largely switched to MLRS; rocket batteries can get a lot more rounds off in those couple of minutes than guns can.

Of course, the less equipment you have, the easier it is to leave. And when it comes to the rocket/mortar fire being directed at our encampments in Iraq, it doesn't take the attackers long at all. A big mortar tube can be broken into man-carriable components in about ten seconds; a small mortar tube can be carried by one man. And in any case mortar tubes are cheap and plentiful; if necessary they can be abandoned.

These are harassing attacks. They're small and brief and almost always ineffectual. If you're thinking of this as saturation shelling, think again.

Their primary purpose is to get headlines, to intimidate American soldiers, and to hope for a lucky direct hit on something important. The bases they're attacking are big and spread out, with most of the tents and other structures protected against fragments by walls of sandbags, and mostly those mortar rounds don't hit anything or cause any harm at all.

They're trying to provoke us into returning fire. That would please them just fine. The militants make their attacks from populated areas, fire a couple of rounds, pick up and leave. If they're disciplined, they're vulnerable for maybe 30 seconds. Even with our ultra-fast response rate, we can't return fire before they're out of there, and even if we did, we'd kill a lot of civilians as well.

If they were stupid enough to make such an attack from an unpopulated area, we'd nail them. That happened a few times in Afghanistan in 2002, in fact, but not by radar-directed counterbattery fire. The attackers were found by attack helicopters as they tried to hike out of the area. But in Iraq what you're talking about is maybe three men with one mortar tube and five shells who move into a city street, set up their tube, fire off their rounds (five rounds takes about ten seconds), break down their tube, and get their butts out of there, vanishing into the city.

Or their mortar may be mounted on the back of a pickup truck, making it a form of improvised self-propelled artillery. In that case they'll be moving within seconds of the last shell being fired.

The only way to stop these kinds of mortar attacks is to find the attackers later and take them out. It isn't going to happen at the time of the attack. Those mortar attacks will stop when we've gutted the insurgency. Until then we just have to put up with them.

Update: Robin Goodfellow points out that there are technologies in the pipeline which may be able to detonate those kinds of mortar shells in the air before they hit. He's right, but they won't be showing up in Iraq any time soon. (The "near future" is five to ten years, not two weeks.)