The Soviet ship Alexsandr Ulyanov, bound for Nicaragua, finished its passage through the Panama Canal yesterday with the help of U.S. technicians.

The ship is the first of at least half a dozen ships, according to Pentagon officials, carrying military equipment from eastern Europe or the Soviet Union to the Pacific port of Corinto in Nicaragua.

The Nicaraguan government says the ships are carrying civilian goods.

President Reagan cited the Ulyanov in his news conference Tuesday night as evidence that the United States is not threatening anyone's ships on the high seas.

"It is carrying a load of military equipment, helicopters for military purposes and so forth," Reagan said. "And no one shot at them."

Reagan could have cited the ship's two-day unimpeded passage through the canal as further evidence of his peaceful intentions.

Although the United States has ceded the canal to Panama, the waterway is still under the day-to-day control of the Panama Canal Commission, a U.S. agency.

"First we give the canal away," a Pentagon official grumbled. "Then we let the Russians through with arms." Meanwhile, Cesar Delgadillo, director of the Nicaraguan ports agency, told the Associated Press that the expected Soviet ships are carrying medicines, grain, farm machinery and other civilian goods.

"These ships come loaded with aid for the people of Nicaragua, and not arms, as the North American government says," Delgadillo said.

But Nicaraguan Foreign Minister Miguel D'Escoto did not deny the presence of arms when questioned by ABC news. "You cannot ask a country that is suffering aggression not to arm themselves," he said. "It's absurd."