Pakistan's government ordered the army to eliminate militants today, setting the stage for a major offensive against Taliban fighters battling security forces in a northwestern valley.
The government's handling of the Swat valley has become a test of its resolve to fight a growing Taliban insurgency that has alarmed the United States.
President Asif Ali Zardari, in Washington for talks, assured US president Barack Obama on Wednesday of Islamabad's commitment to defeating al Qaeda and its allies.
Security forces used jets and helicopters to pound Taliban positions in Swat, 130 km (80 miles) from Islamabad, as thousands of civilians took advantage of a break in a curfew to flee.
With hundreds of thousand of people already displaced by fighting, aid groups said the new exodus of tens of thousands was intensifying a humanitarian crisis.
Prime minister Yusuf Raza Gilani said in a televised address the militants were trying to hold the country hostage at gunpoint.
"Decisive steps have to be taken," Mr Gilani said.
"In order to restore honour and dignity of our homeland and to protect the people, the armed forces have been called in to eliminate the militants and terrorists."
Gilani did not announce the launching of an offensive but said the government would not bow before terrorists and would force them to lay down their arms.
Reinforcements have been arriving in Swat as a peace pact collapsed. On Wednesday, soldiers launched assaults in the outskirts of the region's main town of Mingora, where the Taliban have occupied important buildings.
Authorities agreed in February to a Taliban demand for the introduction of Islamic sharia law in the former tourist valley but the militants refused to disarm, and pushed out of Swat closer to nuclear-armed Pakistan's capital.
That raised alarm in the United States. Pakistani action against militants in its northwest is vital for US efforts to defeat al Qaeda and stabilise Afghanistan.
US secretary of state Hillary Clinton accused Islamabad of abdicating to the Taliban while Mr Obama expressed grave concern about the "very fragile" government.
Security forces launched an offensive on April 26th to expel militants from two of Swat's neighbouring districts, Dir and Buner, and security has deteriorated sharply in Swat since then.
Army chief General Ashfaq Kayani told his top commanders earlier the army was fully aware of the gravity of the internal threat and would "employ requisite resources to ensure a decisive ascendancy over the militants."
US defence secretary Robert Gates, speaking to reporters in Kabul shortly before Mr Gilani's announcement, said the Taliban had overreached by attacking Buner, 100 km (60 miles) from Islamabad, and he was "very satisfied" with the Pakistani response.
Reuters