Ethiopia's offensive against Somali guerrilla forces in the Ogaden "is so great that it must be aimed at more than just" the debilitated guerrila army struggling to maintain a foothold here near the border, rebel commander Asoul Shirdo said. It is rather aimed "at Somalia itself".

Six months into an Ethiopian offensive that has driven guerrilas of the Western Somali Liberation Front out of much of the disputed Ogaden, the deterioration in the rebel position is sharply illustrated by their current inability to take reporters far into the desolate, inhospitable region.

As recently as July, visitors were taken approximately 225 miles deep into the territory by the guerillas and were even able to go to the outskirts of the few towns and cities that the Ethiopians then still controlled, and often within sight of Ethiopian defensive positions.

During a five-day period late last month, the front was able only to organize two brief forays of a few hours each into areas of the Ogaden very close to the border.

The Ethiopian Army is now positioned along the contested border to threaten an invasion, should it choose to do so. It is a move that could have grave repercussions on the U.S. plans to use a Somali naval and air base at Berbera, about 150 miles from the border.

Liberation front commanders admit that their forces have had to pull back or disperse inside the Ogaden in the face of vastly superior Ethiopian numbers and material in the last few months. According to Somali officials, following a series of victories in July and August, Ethiopian forces have crossed the border on three occasions and driven more than 15 miles into Somalia.

"Literally, we are defenseless, we are at the mercy of the Ethiopians," said Somali Finance Minister Abdullahi Addou, a key foreign policy aide to President Mohammed Siad Barre in an interview in the capital of Mogadishu. He said they feared an imminent invasion.

The government maintains that the guerillas, whom it backs but officially does not aid with its own troops, are the only force now fighting the Ethiopians.

At Bolol staging base, about 125 miles northwest of Hageysa and just two miles inside Ethiopian territory, Commander Shirdo said it would be too dangerous to travel any further than the two brief trips inside the Ogaden except on foot because the roads were mined and the Ethiopian forces were only about 10 miles away.

Two days later it was possible to cross the unmarked border at Ina-Guha, about 55 miles southwest of Hargeysa. The Land Rover was forced, however, to leave the rutted track and drive overland to avoid mines and possible encounters with Ethiopian troops.

After bouncing over about 20 miles of parched land, the party was halted by two shots fired from a guerrilla encampment. After an hour of debate the nervous local commander, Abdullahi Habil, refused to let the group continue.

Aside from the danger of encountering the enemy, there was also concern about possible espionage. It was explained that a French reporter recently had been taken through a village in the area that later was napalmed by Ethiopian jets. The villagers were convinced that the reporters had provided logistical information to the Ethiopians.

The guerrillas also have been unable to attack Ethiopia's vital rail link to Djibouti since the Addis Ababa government sent in reinforcements a year ago.

The main problem for the guerrillas is that they are badly outgunned. The most modern equipment they displayed consisted of rocket-propelled grenades and bazookas capable of knocking out tanks and armored personnel carriers, but they have nothing to combat the Cuban-manned Soviet artillery used by the Ethiopians.

The guerrillas, many of whom were trained in Cuba and the Soviet Union before the Communist Bloc shifted sides, also have no antiaircraft missiles to defend against the jet attacks.

For the most part the shabbily clad guerrillas are armed with the ubiquitous Soviet-designed AK47 rifles, the Third World symbol of revolution. Most of the weapons, according to Commander Shirdo, have been "provided" by the Ethiopians when their convoys were ambushed.

Some of the liberation front's forces are armed with a pre-World War II Italian 7.25 mm, six-shot rifle they call lihle ("gun of six").

Ironically, the guerrillas are about as poorly equipped as the Ethiopians themselves were when they vainly tried to resist Mussolini's army during the Italian conquest of the country in 1935.

Talks with the guerrillas bear out Western analysts' prognoses that neither side seems able to win the war and that a peaceful settlement appears remote.

"We are all here and we'll die here if necessary," Shirdo said, sitting under a tree at the base.

Sharif Hussein, the guerrila commander for the northern sector, refuses to disclose how many troops he has, but diplomatic sources estimate the number at something higher than 10,000, many of them teenagers or younger.

It is estimated that Ethiopia has committed 100,000 troops to the Ogaden despite wars against dissident elements on several other fronts.

The high desert terrain in much of the Ogaden does not lend itself to traditional guerrilla warfare and there have been a number of set battles with heavy casualties. It is estimated that about 25,000 were killed in the brief 1977-78 war -- about the number killed during the entire seven-year war for black-majority rule in Zimbabwe.

Ethiopian victories this July and August at Warder, Dagehabur and Biayakule were followed by pushes on the southern front toward the border. The guerrillas say the Ethiopians have warned the nomadic population to clear out of a nine-mile strip along the entire 1,500-mile border.

In late August, Ethiopian ground troops crossed the border for the first time at Goreya-Owl and attacked a Somali Army garrison. Until then Somalia, which supports the guerrillas, had only been subject to attack by Ethiopian jets.

In September and October, the Ethiopians drove up to 15 miles inside Somalia at Dolo and Yet on the southern front and in both cases held the areas for several days.

Despite the Somali fears, many analysts feel that the Ethiopians will stop short of an all-out envasion of Somalia, since most of Addis Ababa's support in Africa is based on the argument that Somalia is violating a recognized border.

It is more likely that the incursions are designed to destabilize the government of Siad Barre, who recently declared a state of emerency.

Ethiopia supports a small dissident group called the Somali Salvation Front. It is always possible that a deep penetration could be launched under the guise of the front.

In the event of such an attack, "it is an open question whether Siad Barre could survive politically," a Western diplomat said.