KABUL – Civilian casualties are rising in Afghanistan as U.S. and NATO reinforcements stream into the country as part of a military buildup to combat the resurgent Taliban, the Interior Ministry said Sunday.

There have been 173 civilian deaths in violence in Afghanistan from March 21 to April 21, marking a 33 percent increase over the same time period last year, the ministry said.

Civilian deaths at the hands of U.S. and other international forces are highly sensitive in Afghanistan, although the United Nations says the Taliban are responsible for most civilian casualties. Still, the backlash could undermine U.S. strategy ahead of a summer military operation in Kandahar, a key southern city that is the spiritual home of the Taliban.

The goal of the U.S.-led operation is to flood in troops, rout the militants and rush in new governance and development projects to win the loyalty of Kandahar’s half-million residents.

Public outrage over civilian deaths prompted top commander Gen. Stanley McChrystal last year to tighten the rules on the use of airstrikes and other weaponry if civilians are at risk.

There are fears the problem could get worse with 30,000 U.S. and NATO reinforcements heading to Afghanistan as part of a military buildup to take on the Taliban in the south.