The Pakistan Army on Wednesday widened its crackdown on the Taliban and attacked them with helicopter gunships and tanks to wrest control of the restive Swat valley killing 64 extremists as thousands of people fled Mingora following an upsurge in violence. The action by the Pakistani security forces came as the trilateral summit of the US,Afghanistan and Pakistan got underway in Washington on Wednesday,with Pakistan President Asif Ali Zardari assuring his host that Islamabads commitments to flush out militants will not waiver. Under pressure from the US to act against al-Qaeda and Taliban,Zardari promised to do so and said only a democratic Government can successfully eliminate terrorism from the region. For no matter how long it takes and what it takes,democracies will deliver. My democracy will deliver, Zardari said in his opening remarks at start of the first day of the meeting. We stand with our brother Karzai and the people of Afghanistan against this common threat,this menace,which I have called a cancer, Zardari said as the summit commenced with a meeting of the two Presidents with Secretary of State Hillary Clinton. Stating that Pakistan carries a huge burden,confronting al-Qaeda and Taliban together,Zardari said: We are up to the challenge,because we are the democracy,and democracy is the only cure to this challenge. Todays discussions will centre on concrete initiatives. I like to know specifically what were going to try to do together. I like us to reach an agreement on that and then to specify the steps will take together to achieve our common goals, Hillary asserted in her opening remarks of the meeting which she termed as historic. Hillary described terrorism as a common threat and said all parties should come together to fight the scourge. Karzai said terrorism is a cancer for both Afghanistan and Pakistan and the two countries should join hands in the fight against terror. Angry over killings of more than 100 people in the US air strikes in Afghanistan this week,President Hamid Karzai said such casualties has been resulting in resentment of people in his country. We hope we can work together towards reducing and eventually completely removing the possibilities of civilian casualties,as we move ahead in our war against terrorism,or in our struggle against terrorism, Karzai said in his statement at the start of the second trilateral meeting between the US,Pakistan and Afghanistan. Hillary regretted the deaths of civilians in Afghanistan in airstrikes targeting militants,saying I want to convey to the people of both Afghanistan and Pakistan that. we will work very hard with your governments and with your leaders to avoid the loss of innocent civilian life. Earlier,Hillary and US special envoy Richard Holbrooke held an unscheduled meeting with Zardari,officials said. Zardari and Karzai were due to hold a meeting at the White House with US President Barack Obama later in the day. Widening its crackdown on Taliban,the Pakistan Army on Wednesday attacked militants with helicopter gunships and tanks,as troops rolled in to wrest control of the restive Swat valley killing 62 extremists in one of the most bloodiest fightings. Heavy fighting also raged in Buner district where troops blasted Taliban fortifications in Pir Baba and Sultanwas areas. Shells and rockets landed on Mingora,the main town in the valley,where Taliban seized all major Government buildings,including that of the local mayor and DIG of Police,and mined all thoroughfares in anticipation of a land assault. Taliban spokesman Muslim Khan claimed the militants were in control of 90 per cent of Swat and were acting in response to the Armys violations of the peace deal.