Tallil Airfield, southern Iraq ? With the arrival of a C-130 transport plane, Iraq’s second-largest airfield took a crucial role Thursday in American war strategy — a way to sidestep Iraqi attacks on supply lines, and get the troops what they need.

Tallil airfield, mothballed since the 1991 Gulf War, was captured by U.S. soldiers on Saturday. It is now an important forward base on the way to Baghdad; supplies and men can be delivered here, without having to travel by ground from Kuwait and risk bloody encounters with Iraqi forces still roiling the south.

This is, a hastily posted sign declared, “Bush International Airport.” The immediate goal: to speed all the stuff of war — fuel, ammunition, water, food, reinforcements — to the front, shortening supply lines that had extended as much as 200 miles into Iraq.

There were reports of some shortages Thursday, as U.S. and British troops continued to encounter unexpectedly fierce resistance throughout the south. Some Marines were being issued two meal packets every 36 hours; normally, they get three meals a day.

Brig. Gen. Vincent Brooks, a spokesman for the central command, said he had not heard of any shortfalls of supplies. “We haven’t had any problems that would hinder operations at this point,” he said.

He insisted that plans for the war were working.

But the fight continued around An Nasiriyah, the key city on the Euphrates River. Brooks told reporters merely that some Marines had been injured in a 90-minute battle in the area. But officials at Camp Lejeune, N.C., where the troops are based, said 25 Marines were wounded or missing.

“There are a lot of forces out there that still want to fight. They didn’t exactly roll over and surrender,” said a Marine helicopter pilot who would use only his nickname, Lurch. “We are so wrapped up in not creating collateral damage that we are leaving great enemy strongholds behind.”

Fighting continued as Basra, as well, and at Najaf, less than 100 miles from Baghdad, where units of the Army’s 3d Infantry Division had encircled the city and were fighting Iraqi reinforcements from Baghdad, according to Steven Lee Myers, a New York Times reporter who spoke on CNN.

In the north, cargo planes delivered military supplies a day after 1,000 American airborne troops parachuted in to seize an airfield.

The seizure of Tallil and the northern airfield is “not only a monumental step forward but absolutely essential,” said military analyst John Abrams, a retired Army general.

For the moment, controlling the bases instantly and dramatically shortens supply lines, reducing their dependence on hundreds of miles of roads where convoys were exposed to hit-and-run attacks by Iraq’s Fedayeen and other irregular troops.