Janet Napolitano, the secretary of homeland security, who spoke at the conference, described the agency’s shift as a “risk-based approach that attempts to segregate out passengers for whom we have a lot of information and can evaluate their risk as low-risk versus those that we know little about or that are higher risk.”

The T.S.A. also plans to focus more on devices that could do catastrophic damage to an aircraft. John S. Pistole, the agency’s administrator, announced that small pocketknives and some sports equipment would be allowed in carry-on bags beginning April 25 — an effort to more closely align American rules with European standards.

The American government would also like to expand its use of behavior detection officers who question passengers in security lines, a technique used in Israel, but the Government Accountability Office has faulted the way the program is being carried out in the United States, saying it has not met scientific standards of validation.

While airlines and equipment manufacturers are seeking similar security procedures worldwide, sharing travelers’ data across borders — which already happens to some degree — presents more complex challenges. Governments are debating when and how to recognize another country’s trusted travelers, and how to respond if nations like China start asking for the same level of passenger data that the United States demands.

The debate is likely to become more heated as civil rights groups and passengers — two groups unrepresented at the conference — get a clearer sense of where trusted traveler programs are headed.

“The notion that the government is in any position to judge who is trusted and who is risky is very problematic,” said Jay Stanley, a senior policy analyst at the American Civil Liberties Union. “Terrorist attacks on airlines are basically freak events — fortunately, they’re exceedingly rare — so any attempt to predict who is likely to engage in that type of thing is inevitably going to sweep up a vast number of innocent people.”

That has been the case with the government’s Global Entry program, a trusted-traveler initiative that allows members who have undergone background checks to use a kiosk to clear customs instead of waiting to speak with an agent. Members also gain access to PreCheck lanes for expedited security screening at some airports.