(CNN) A group of more than 100 former national security heavyweights from both political parties protested President Donald Trump's executive order on refugees in a letter Monday, calling on the heads of three US government agencies to use their own power to ease some of the restrictions.

"This Order not only jeopardizes tens of thousands of lives," they wrote, "it has caused a crisis right here in America and will do long-term damage to our national security."

The letter's signatories are former Cabinet secretaries, generals and high-ranking officials from Democratic and Republican administrations, including Secretary of State Madeleine Albright, Secretary of Homeland Security Janet Napolitano, National Security Adviser Susan Rice and Director of the CIA Michael Hayden.

"Many of us have worked for years to keep America safe from terrorists," they wrote. "Many of us were on the job working for our country on 9/11 and need no reminder just how vital it is to destroy terrorist networks and bring partners to our side in that global effort."

"Simply put," they continued, "this Order will harm our national security."

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