Authorities are going to begin random inspections of bags entering the subway system in the U.S. capital, a program based on similar efforts in Boston, Massachusetts, and New York City.

Metro Transit Police Department Chief Michael Taborn said Thursday the inspections have been in the works for years, and are not a response to any particular threat. In recent months, authorities say the subway system has faced various threats.

A man was accused of researching stations in what he thought was an al-Qaida plot to bomb and kill commuters and another man was charged with threatening on Facebook to detonate pipe bombs in the subway system.