Armed officers of the Transportation Security Administration (TSA), traditionally confined to airports, are increasingly patrolling all forms of mass transportation and public events, according to a report published Monday in the New York Times. The TSA’s Visible Intermodal Prevention and Response (VIPR) squads are deployed across the US to perform random security sweeps, in the name of stopping terrorism.

The VIPR teams have been used in Amtrak stations, bus terminals, and sporting events such as the Superbowl and Indianapolis 500, as well as rodeos, music festivals, the Mall of America, the Democratic and Republican national conventions, the Presidential Inauguration, the State of the Union Address and the United Nations General Assembly.

The Times reported, based on TSA records, that the department operated nearly 9,000 checkpoints and mass searches at such events. VIPR units generally consist of air marshals and baggage inspectors, many of whom are former members of the military or other police forces. They also often include bomb-sniffing dogs and  plainclothes officers to monitor crowds for what is deemed to be suspicious activity.

The Times piece described a joint operation in 2012 involving VIPR teams, Houston police and local transportation officers randomly stopping passengers, searching bags and asking security questions. The sweep resulted in a handful of arrests, mostly for outstanding drug possession and prostitution warrants.

The TSA employs 56,000 people at 450 US airports, according to the Times. It was created in the wake of the 9/11 attacks to conduct security checks of passengers and baggage at airports and was folded into the Department of Homeland Security, which itself has more than 200,000 employees.

In recent years, the TSA has been the center of various attacks against constitutional protections of unreasonable searches and seizures, including “enhanced” pat-downs by TSA agents, full-body scans and random searches inside airports. Those who refuse the screening measures can be subject to civil penalties.

The VIPR program was created in 2005 after the Madrid train bombing in 2004 that killed 191 people. Under the pretext of needing to cover not only airports but all forms of mass transportation, the teams were created to patrol train and bus terminals in coordination with local law enforcement.

The use of VIPR patrols has been significantly expanded during the Obama administration. In 2008, there were only 10 such units. Now, the program has 37 teams, several hundred personnel, and a budget of $100 million.

The TSA’s web site explains its expansion from screening luggage to providing security at sporting events is the need to develop “partnerships and increasing interagency communications”. In other words, the TSA VIPR teams are a significant component of the emergence of a federally controlled police force.

Agency officials refused to release details to the New York Times over whether VIPR teams have ever foiled a terrorist plot or any major threat to public safety, claiming that the information is classified. They only say that random searches and the increased police presence is a necessary deterrent to “terrorism.”

VIPR teams have drawn criticisms for carrying out warrantless searches, despite the fact that the searches are “voluntary”. In fact, people who attempt to assert their rights and refuse to be searched run the risk of being escorted off a train or out of an event.

“The problem with T.S.A. stopping and searching people in public places outside the airport is that there are no real legal standards, or probable cause,” Khaliah Barnes, administrative law counsel at the Electronic Privacy Information Center in Washington, told the Times. “It’s something that is easily abused because the reason that they are conducting the stops is shrouded in secrecy.”

The expansion of TSA patrols comes after the US Government Accountability Office (GAO) released a report last week showing an increase in misconduct among TSA personnel. From 2010 to 2012, offenses of TSA agents rose 26 percent to approximately 9,600 cases. This includes one officer at the Orlando International Airport who pled guilty in 2011 to embezzlement and theft after stealing $80,000 of electronics from passenger luggage.

In another incident, not included in the GAO report, one TSA agent at Newark Liberty International Airport was convicted of stealing $800,000 worth of cameras, laptops, and other items.  The report also found that there is not a proper procedure for reviewing or recording cases in order to follow up and mitigate future instances of misconduct.