A collective bargaining agreement (CBA) is a contract between an employer and a labor union regulating the terms and conditions of employment for unionized employees. The Department of Homeland Security (DHS) oversees agencies like the Transportation Security Administration (TSA). The DHS decision impacts TSA employees' union representation. - The Department of Homeland Security (DHS) terminated its collective bargaining agreement with the Transportation Security Administration (TSA). - The DHS claims the union has allowed 'poor performers' to remain in their positions, undermining security. - A union representing TSA workers has characterized the DHS decision as an 'unprovoked attack' and vowed to fight it. - The move affects over 50,000 Transportation Security Administration officers who oversee security checkpoints at American airports and transportation hubs.