Britain's emphasis on defense, Mr. Fraser said, plays up a competitive advantage over France and Germany. Both spend proportionately less on their militaries and are not as closely integrated in security matters with the United States.
In addition to greater spending on hardware, Britain confirmed the creation of a National Cyber Force, a joint venture of the Defense Ministry and GCHQ, the electronic surveillance agency. Since April, it has been conducting offensive cyberwarfare operations against hostile states, terrorists and criminal organizations, not unlike the mission of the United States Cyber Command.
"This is a clear and loud message to the Biden administration that even if you don't agree with Brexit, there are still many ways the U.K. can be an important partner to the U.S. -- and in security, the most important partner," said Malcolm Chalmers, the deputy director of the Royal United Services Institute.
Still, as several experts noted, Mr. Johnson's bid to be useful to Mr. Biden will mean far less if Britain fails to strike a trade deal with Brussels. A yearlong transition period is set to expire on Jan. 1, and economists warn that not having a new agreement to take its place would do serious harm.
A long-term rift between America's closest European allies would be an unwelcome greeting for a president who already thought Brexit was a bad idea.
"The logical third thing we should expect is a Brexit deal in the coming weeks," Mr. Fraser said. "Not to do one in the current circumstances would be doubly ill-advised because of the Biden factor."