Ethiopian troops have carved out a huge swathe of Eritrean territory in the past 12 days, forcing their enemy into a series of humiliating retreats and causing more than 100,000 people to flee into neighbouring Sudan.

Eritrean President Isayas Afewerki says his country can and will fight back, but analysts believe the Red Sea state simply does not have the capacity to sustain a long, conventional war.

``For 30 years the Eritreans fought a guerrilla war against Ethiopia and, in effect, they won that,'' said a Nairobi-based Western diplomat.

``But this is different. This is two sovereign states with two national armies slugging it out -- and it looks like Ethiopia has won it.''

On paper, it is hardly surprising.

The International Institute of Strategic Studies estimates that Ethiopia has an army of nearly 300,000 troops lined up against Eritrea's 180,000.

While both countries have spent heavily on military hardware since the border war first erupted two years ago, Ethiopia has a vastly superior air force, more heavy artillery and simply more people to call up from among its 60 million population.

Eritrea, however, does have some cards up its sleeve.

While its four million people are dwarfed by the Ethiopian population comprising dozens of tribes and ethnic groups, most Eritreans are ideologically united against Addis Ababa after their 30-year guerrilla war.

ERITREANS USED TO SPARTAN EXISTENCE

In that time the Eritrean People's Liberation Front (EPLF) lived a spartan existence, expert at living off the land and equipping themselves from scraps left over from their battles with the Ethiopian military.

Their struggle only ended when they joined forces with a coalition of forces led by the Tigrayan People's Liberation Front to overthrow the Marxist military regime of Mengistu Haile Mariam.

They enjoyed good relations until two years ago when a border row erupted into warfare. Eritrean troops initially routed the Ethiopians and although Ethiopia regained some territory last year and again in the past 12 days it says Eritrean troops still occupy some of its land.

Eritreans say they will have no hesitation in going ``back to the bush'' to fight Ethiopia, and they may also have time and the weather on their side.

The first six months of the year have proved critical in all conflicts in the Horn of Africa and this one is no different.

The war started in this period two years ago, flared anew at the same time last year and erupted again 12 days ago.

Ethiopia's recent successes have come because at this time of the year its forces have been able to cross the Mereb river -- which divides the two countries along much of their border -- at virtually any point.

But rains are expected in the next few weeks and if the river floods as normal, crossing points will be limited and the Ethiopians will either have to withdraw or face the prospect of fighting with only limited support from the rear.

This happened to a succession of Ethiopian armies sent to crush the EPLF: they would make gains when supply lines were open and be beaten back during the wet season.

``The last thing the Ethiopians want is to find themselves in two months time in the same position they are now,'' a diplomat said. ``They could find themselves stuck.''

Ethiopia is clearly seeking a quick, decisive military victory, not necessarily in Asmara itself, which will force Eritrea to effectively surrender and accept Addis Ababa's terms at the negotiating table.

But if Eritrea can hold out, Ethiopia might find itself in another quagmire, its army running out of food and supplies and hit from all sides by an enemy who returns to his old EPLF hit-and-run tactics