Terrorist groups are believed to be actively recruiting Western Europeans for possible attacks in Europe, or to use the continent as a springboard for strikes in the United States, US Homeland Security Chief Michael Chertoff said Tuesday. "Europe is a place where we have seen attacks carried out. It's a place where we know they are recruiting operatives who can pass freely in Western Europe," Chertoff told reporters. "Whether the attack is aimed at Western Europe or aimed at coming to the US from Western Europe, that's one of the things we have to be focused on." Chertoff, in Warsaw for ceremonies marking the 65th anniversary of the Warsaw ghetto uprising against the Nazis, said terrorists are looking to recruit people who do not fit the "stereotype of what a terrorist looks like ... (people) who are Western in appearance, Western in experience, can mingle freely in the West without attracting attention, who will be easier to slip into the stream of travel." "The hardest person to detect is someone who comes in with a clean record, a legitimate passport, an easy understanding of how to operate in the West because they've grown up there, and an intent to carry out a murderous act," he said. To combat this perceived threat, Chertoff said the US is working to collect more information, including biometric details on individuals, "to make it harder for people to slip under the radar." In other comments, Chertoff echoed warnings from other top US officials on Pakistan, saying that without a "significant clamping down on the ability of al-Qaida and similar groups to operate in the frontier area" between Pakistan and Afghanistan, the region is going to remain a "strategic concern." He added that it was too early to tell what impact the new government in Islamabad might have on the fight with terrorism in the border area. "It's a new government. I think we have to give it time to get its sea-legs, so to speak," he said. "I think we will be watching to see how they move forward in dealing with this threat."