More than 100 high-level former Republican national security officials, former GOP members of Congress, former Ambassadors and other high-profile Republicans are signatories to a scathing letter stating that Donald J. Trump is “unfit to serve again as president” and endorsing Kamala Harris, although they might disagree with her on several issues. Here is the letter. It is also available HERE. We are former national security and foreign policy officials who served in the administrations of Presidents Ronald Reagan, George H.W. Bush, George W. Bush, and/or Donald Trump, or as Republican Members …