By Dan Merica CNN

(CNN) -- President Donald Trump signed an executive action on Monday that implemented a hiring freeze for some federal workers in an effort to cut government payrolls.

The move, which had long been promised by the Trump administration, does not include military employees, a fact Trump made clear during the signing.

"This memorandum counters the dramatic expansion of the federal workforce in recent years," Sean Spicer, Trump's press secretary, said Monday. "In particular, it prevents filling vacant positions and creating new positions except when necessary to meet national or public security responsibilities."

He added: "It does not apply to military personnel, and it ensures that the American taxpayers get effective and efficient government."

The freeze also includes preventing the hiring of federal contractors: "Contracting outside the Government to circumvent the intent of this memorandum shall not be permitted."

Trump's executive action makes good on a promise the Republican made on the campaign trail and mimics what other presidents have signed.

Total executive branch federal government employment -- not including uniformed military personnel and legislative and judicial branch personnel -- has dropped dramatically since the high point in the late 1980s and early 1990s when it averaged about 3 million employees. In recent years (such as 2009-2014) it has continued to decrease, at a slower rate, from 2.77 in 2009 to 2.66 in 2014.

The American Federation of Government Employees, the primary union that represented federal employees, blasted the announcement.

"President Trump's action will disrupt government programs and services that benefit everyone and actually increase taxpayer costs by forcing agencies to hire more expensive contractors to do work that civilian government employees are already doing for far less," J. David Cox Sr., the group's president, said in a statement.

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