MARGARET WARNER: One after another, Pakistani military convoys rolled toward the fighting today, as tens of thousands of civilians fled from it.
HAZRAT NAWAB (through translator): People are traveling on foot. There is no transportation. We are in trouble.
MARGARET WARNER: The U.N. says 250,000 people have been displaced, and they expect that number to double, as the army steps up operations against Taliban strongholds in the Swat Valley, in Pakistan's Northwest Frontier province.
Civilians in the valley's main city, Mingora, say they're being caught in the crossfire.
PAKISTANI CITIZEN (through translator): From the sky, there's shelling and heavy artillery and from jet bombardment. We think they're going to target us. Therefore, we are not at peace.
And from the army side, there is also no safety. And we don't know from which direction they are targeting us and killing the people.
MARGARET WARNER: Military officials showed photographs of captured insurgents and insisted it was the Taliban putting civilians at risk.
MAJ. GEN. ATHAR ABBAS, Pakistani Military Spokesman: They are on the run and trying to block the exodus of civilians from the area. During the last 24 hours, approximately over 140 militants have been killed in different areas.
MARGARET WARNER: The army launched this latest offensive Wednesday. It came after the Taliban broke the terms of a peace deal with the government in Swat and moved to seize territory in nearby Buner province, just 60 miles from the capital, Islamabad.
Pakistani President Asif Ali Zardari was in Washington this week for meetings with President Obama and Afghanistan President Hamid Karzai.
I talked to President Zardari about his country's fight against the militants today, at his Washington hotel.