The Russian military is learning once again some of the central principles of counter-guerrilla warfare.

The latest setbacks for Russian forces in Chechnya, with Chechen fighters attacking buildings in Russian-held towns like Argun and Shali, indicates the scale of the military problem facing Moscow's generals.

The Russians have an overwhelming superiority in numbers and firepower.

There are estimated to be between 3,000 and 5,000 Chechen fighters in the Grozny area. Russia has deployed up to 130,000 troops in this campaign.

But Russian forces are dispersed over a large area and have proved incapable of preventing Chechen attacks even in places thought to have been secured.

Uphill struggle

Nonetheless western military experts down-play the strategic significance of these Russian reverses.

The Chechens are at their strongest when using hit and run tactics, but the experts believe that Russian forces can still prevail.

However, they say that it is going to be an uphill struggle.

Despite its poor performance, the Russian army can still take Grozny, the western analysts believe, but only if it is prepared to accept significant casualties.

Traditional Soviet military doctrine requires a six to one superiority on the part of the attacker in urban warfare. But fighting in the rubble of a city like Grozny makes it very difficult for an attacker to mass such forces.

Putin's war

Russian generals can wear down their Chechen opponents by recourse to their massive firepower - especially artillery and rockets.

A very slow grinding battle for Grozny will mean heavy Russian casualties, but acting President Vladimir Putin may have little other choice.

This is very much Mr Putin's war but the experts believe that huge problems still lie ahead.

Even if Grozny is taken, Russia may then have to face a long-running guerrilla struggle that will inflict a regular stream of casualties and weaken its forces already low morale.