ISLAMABAD - US Assistant Secretary of State for South and Central Asia Richard Boucher Monday said Mumbai attackers had links that lead to Pakistani soil. "India and Pakistan have to work together to investigate the Mumbai attacks and those behind the carnage will only be found if the South Asian rivals cooperate," Boucher told reporters at US Embassy after spending a busy day here. India handed over what it said was evidence linking terrorists who attacked Mumbai in November to elements in Pakistan, which Boucher described as a positive step. Boucher refused to reveal any details of the evidence he had seen, but said it was "clear that the attackers had links that lead to Pakistani soil.""Each side has pieces of the puzzle and they need to be known to each other," he stated, adding, "The two sides need to exchange information. People have to work with each other," Boucher advised. He, however, said Pakistan's crackdown on Jamaatud Dawa, a charity with links to Lashkar-e-Taiba, showed the country's commitment to eliminate sources of terrorism on Pakistani soil. "There is determination here to follow up and find the groups that are responsible, so they never do it again," he said. Agencies add: Boucher welcomed the Indian decision to share information with Pakistan and said, "People in Pakistan have determination to find those responsible and those who did it." Boucher said that he was glad to know India provided information to Pakistan, adding that Washington had tried to encourage India to share information with Pakistan. To a question about the situation along the borders after Pakistan pulled out troops from the tribal region and deployed along Indian borders, Boucher said, "The situation is calm on the borders." He said that the US had encouraged both sides not to push for military confrontation and the best way was to do through dialogue. Boucher said that during his meetings in Islamabad, he found that Pakistan had shown determination to deal with both the groups and individuals in terms of taking actions against them. "Pakistan has done quite a lot," he said. He added that Pakistan and India must deal with those who harmed the Kashmir issue and were involved in what he called terrorist activities. He stressed that the two sides must exchange information to stop future attacks. "Both are working how to develop the probe," he said. "Let's find whoever were to be involved. We are talking to both. We have direct interest as six US citizens were killed. We are interested that the responsible must be found," he said. He said that Indian investigations were advancing, adding that he would also visit India. He said that Pakistan had also arrested several people of the banned Jamaatud Daawa and closed their offices. "Pakistan is serious to deal with the threat of terrorism," he said.