A car bomb killed 100 people in a crowded market in Pakistan's city of Peshawar today, just hours after US secretary of state Hillary Clinton arrived in the country pledging a fresh start in sometimes strained relations.
The bomb, the latest urban attack since the army began a major assault on rural Taliban strongholds two weeks ago, was the deadliest since 2007 when around 140 died at a procession to welcome home former prime minister Benazir Bhutto, who was assassinated just weeks later.
A doctor at Peshawar's main hospital said the victims of the bomb were mostly women and children. At least 200 people were injured in the attack.
The bomb went off in the busy Peepal Mandi market street in a city that for years served as the headquarters of the Pakistan- and US- backed mujahideen war against the Soviet Union's occupation of Afghanistan.
Although nobody claimed responsibility, suspicion immediately fell on Pakistani Taliban militants who are the target of the army offensive.
The rugged landscape between Afghanistan and Pakistan has become a haven for Taliban militants fighting on both sides of the border as well as many hundreds of al-Qaeda operatives and other foreign Islamist insurgents.
Hours after the attack, Mrs Clinton told a news conference that Washington fully supported Pakistan's battle.
"I want you to know that this fight is not Pakistan's alone," she said. "So this is our struggle as well and we commend the Pakistani military for their courageous fight and we commit to stand shoulder to shoulder with the Pakistani people in your fight for peace and security.
Pakistani foreign minister Shah Mehmood Qureshi told the news conference with Mrs Clinton that the militants would be crushed. "We are facing this on a daily basis but the resolve and determination will not be shaken," he said.
Addressing those responsible, he added: "We will not buckle. We will fight you. We will fight you because we want stability and peace in Pakistan."
Mrs Clinton acknowledged that misunderstandings dogged US-Pakistan ties and pledged to refocus the relationship on the "needs of the people" including strengthened economic assistance and development of democratic institutions.
She said the main purpose of her trip was to show Pakistan that Washington was a reliable and dependable partner, and to use her own personal style of outreach to bring that message home to the Pakistani people.
Her visit comes amid widespread Pakistani anger over a recent major US aid bill which, despite tripling assistance to $1.5 billion a year for the next five years, has been denounced for imposing conditions critics say violate Pakistani sovereignty.
In the latest fighting in the Waziristan offensive, the army said it had killed 25 militants and captured several training centres and arms caches - including some hidden in caves.
The army says 264 militants and 33 soldiers have been killed since the offensive started. Independent verification is difficult as foreign reporters are barred from the area and it is dangerous even for Pakistani media.