In a blockbuster exclusive, the Global Post reported on one of its blogs yesterday that 7,000 U.S. Marines were on the way to Costa Rica ready for land-based operations. The piece implies that Marines could take an active role in fighting drug trafficking. It’s a sensational story — if only it were true. Marine officials say that, no, they do not have 7,000 Marines on the way to Costa Rica. That’s hardly a surprise, considering the Corps had less than 10,000 Marines in Afghanistan as recently as last year, but it’s worth setting the record straight. What the Corps does…