Tens of thousands of people marched peacefully through the northeastern Italian city of Vicenza under a heavy police presence to protest a planned US military base expansion that has strained relations within the governing center-left coalition. Despite fears that violent demonstrators would be drawn to Saturday's protest, the march took place without incident, finishing outside the main train station where it started as hundred of police officers stood guard and helicopters hovered overhead. The route did not pass the airfield where the expanded base is to be built, where critics keep a permanent picket. "The government majority - whether they agree with the protest or, like me, do not - welcomes that the demonstration in Vicenza finished in an orderly fashion," said Premier Romano Prodi, who had urged protesters to be peaceful. "This must be stressed." Police estimated the crowd at 50,000 to 80,000, while organizers put the numbers at 120,000. "To build a military base is not the gesture of a peaceful government," said 24-year-old city resident Simone Pasin, draped in a rainbow peace flag. "I think it's time to dismantle military bases and put up structures of peace." Trains and buses brought in leftist activists and anti-globalization protesters from across Italy to support residents concerned that the expansion would increase traffic and noise and air pollution, deplete local resources including water and gas, and raise the risk of terrorist attacks. Prodi's government has approved the project, angering his far-left allies. Communist and Greens parties, members of the governing coalition, have backed the protest, though no one from the government showed up after Prodi banned ministers from attending. Prodi has said his government had no reason to halt the expansion, which also has been approved by local authorities. The Ederle base has about 2,900 active duty military personnel. The expansion at the Dal Molin airport, on the other side of town, would allow the US military to move four battalions now based in Germany, raising the number to 5,000. The move is part of the US Army's overall transformation into a lighter, more mobile force - reducing its numbers in Europe from a Cold War high of 480,000 to 88,000 by 2012. Under the plans, elements of the US 173rd Airborne Brigade, a rapid reaction unit now spread between Italy and Germany, would be united. "I think it is a done deal. I don't think there is any turning back. This is what Prodi has said and what the local authorities have said," said David Bustamente, a spokesman at the US Consulate in Milan. "This demonstration is about process." Construction is scheduled to begin later this year and to be completed by 2011 at a total cost of â‚¬439 million (US$576 million). Before construction begins, a task force run by Italians has been set up to hear community concerns and make adjustments to the plans where possible. "We're trying to show sensitivity, because we know people are concerned," Bustamente said. The 173d Airborne Brigade is Europe's quick response force, and is scheduled to redeploy soon for Afghanistan. In 2003, the unit made the biggest airdrop since World War II when its soldiers landed in northern Iraq. Some in Italy's ruling coalition feared the demonstration might suggest anti-US sentiment in the country, but despite the presence of some "Yankees Out!" T-shirts, the mood was more anti-military than anti-American. "The problems is not that Americans are in Vicenza," said Pasin. "The problem is that there is a military base." A group of Americans ignored a warning by the US Embassy to avoid Vicenza and joined the protest behind a banner "Not in our name," receiving cheers by passing Italians who shook their hands and snapped their photos. "The US should not build military bases, the US should think of its domestic problems," said John Gilbert, an American living in Italy for the past 25 years who was in a group of about 20 Americans who had traveled from Rome and Florence.