UNITED NATIONS, NEW YORK — EARLIER this month, after a two-year de facto cease-fire, the Moroccan Air Force attacked Polisario Front positions inside the "no-man's land" that stretches along the Western Sahara's eastern border.Morocco said it had delivered unheeded warnings to the United Nations that the Polisario was violating the peace plan by building permanent structures inside the no-man's land and populating them with pro-Polisario civilians. The Polisario insists that one of the two sites attacked is an undeveloped oasis where nomads gather every summer. "The well isn't even covered," one Polisario official says, "and the civilians were in tents. The Moroccans have again bombed innocent civilians." The Polisario source says that nearby guerrillas shot down two of the attacking Moroccan planes and captured one of the pilots alive. Algeria issued a strong statement warning that they could not stand idly by if the Moroccan attacks continued. Referring to the military operation, King Hassan said in a recent speech: "I wish that this drama [would] end as soon as possible." But on Friday Algerian diplomats reported fresh movements of Moroccan troops in the Western Sahara near the Algerian border. Morocco confirmed troops were on the move, and the Polisario said thousands of civilians were fleeing in advance of these troops.