in 1948 over a new bracero program, Mexico sought to have the United States impose sanctions on American employers of undocumented workers. President Truman signed Public Law 78 (which did not include employer sanctions) in July 1951. Soon after it was signed, United States negotiators met with Mexican officials to prepare a new bilateral agreement. This agreement made it so that the U.S. government were the guarantors of the contract, not U.S. employers. The braceros could not be used as replacement workers for U.S. workers on strike; however, the braceros were not allowed to go on strike or renegotiate wages. The agreement set forth that all negotiations would be between the two governments. A year later, the Immigration and Nationality Act of 1952 was passed by the 82nd United States Congress whereas President Truman vetoed the U.S. House immigration and nationality legislation on June 25, 1952. The H.R. 5678 bill conceded a federal felony for knowingly concealing, harboring, or shielding a foreign national or illegal immigrant. However the Texas Proviso stated that employing unauthorized workers would not constitute as "harboring or concealing" them. This also led to the establishment of the H-2A visa program, which enabled laborers to enter the U.S. for temporary work. There were a number of hearings about the United States–Mexico migration, which overheard complaints about Public Law 78 and how it did not adequately provide them with a reliable supply of workers. Simultaneously, unions complained that the braceros' presence was harmful to U.S. workers. The outcome of this meeting was that the United States ultimately got to decide how the workers would enter the country by way of reception centers set up in various Mexican states and at the United States border. At these reception centers, potential braceros had to pass a series of examinations. The first step in this process required that the workers pass a local level selection before moving onto a regional migratory station where the laborers had to pass a number of physical examinations; lastly, at the U.S. reception centers, workers were inspected by health departments, sprayed with DDT and then were sent to contractors that were looking for workers. To address the overwhelming amount of undocumented migrants in the United States, the Immigration and Naturalization Service launched Operation Wetback in June 1954, as a way to repatriate illegal laborers back to Mexico. The illegal workers who came over to the states