Two decades ago, the drawn-out, disputed conclusion of the 2000 election delayed the transition between Bill Clinton and George W. Bush by 30 days. The 9/11 Commission later found that “this loss of time hampered the new administration in identifying, recruiting, clearing and obtaining Senate confirmation of key appointees” in the national security apparatus, contributing to a lack of preparedness for the terrorist attacks of 9/11.

Nor was it the first time national security issues cropped up during the transition period. In 1988, the terrorist bombing of Pam Am 103, a London-to-New York flight, took place during the transition between the Reagan and Bush administrations.

The 1993 World Trade Center bombing took place one month into President Clinton’s first term. Two months after that, authorities stopped a plot to assassinate President George H.W. Bush on a trip to the Mideast.

“Foreign adversaries believe that the United States is preoccupied during transitions, and it’s in our national security interest to demonstrate that we are not,” is how David Marchick, director of the Center for Presidential Transition, put it to the Washington Post.