During a 33-year career at the Central Intelligence Agency, I served presidents of both parties — three Republicans and three Democrats. I was at President George W. Bush’s side when we were attacked on Sept. 11; as deputy director of the agency, I was with President Obama when we killed Osama bin Laden in 2011.

I am neither a registered Democrat nor a registered Republican. In my 40 years of voting, I have pulled the lever for candidates of both parties. As a government official, I have always been silent about my preference for president.

No longer. On Nov. 8, I will vote for Hillary Clinton. Between now and then, I will do everything I can to ensure that she is elected as our 45th president.

Two strongly held beliefs have brought me to this decision. First, Mrs. Clinton is highly qualified to be commander in chief. I trust she will deliver on the most important duty of a president — keeping our nation safe. Second, Donald J. Trump is not only unqualified for the job, but he may well pose a threat to our national security.