A British Royal Marine takes part in military exercises, Arbroath, Scotland, April 12, 2013.
A British Royal Marine takes part in military exercises, Arbroath, Scotland, April 12, 2013. (Jeff J Mitchell/Getty Images)

On Thursday, voters in Scotland will take part in a referendum that may break apart the United Kingdom. Wednesday, U.S. Marines conducted military exercises alongside their British counterparts in Scotland.

Coincidence? Yes.

Exercise Tartan Eagle -- now in its 14th iteration, according to the Twitter account of the U.S. Marine Corps Forces Europe and Africa -- has taken place since 1994, a joint training operation between British and American Marines, staged both in the United States and Scotland. According to a 2009 U.S. military news release, exercises "included weapons ranges, convoy operations, anti-ambush strategies and navigational classes, as well as a cultural trip to the National Museum of the Marine Corps" in Virginia.

While no one's anticipating unrest following Scotland's referendum, the prospect of Scottish independence raises tricky security questions for a dis-United Kingdom. Britain would have to cede some of its military assets to a new Scottish military and relocate its "Trident" nuclear weapon system, since Scotland's pro-independence campaigners insist their independent Scotland will be nuclear-weapon free. They also intend to be a member of the NATO alliance. Who knows -- joint U.S.-Scottish exercises may soon become as normal an occurrence as Tartan Eagle.