Sometimes they buzz my apartment on the summit of Columbia Heights in northwest Washington, D.C. They're bright red with white stripes and black noses, and they make a noise like giant lawnmowers. They're Eurocopter HH-65C Dolphins belonging to the U.S. Coast Guard, and they've inherited an unusual mission, patrolling the skies over the nation's capital to intercept infiltrating light aircraft like the one that crashed onto White House grounds in 1994.

It used to be this mission belonged to the Customs Service's air branch (PDF!) with its sharp black-and-gold Sikorsky UH-60 Blackhawks, aka "Customshawks". Sharpshooters aboard the aircraft could, in a pinch, put a bullet or twelve into the infiltrator's engine to prevent it crashing into anything important such as, oh, my apartment. Or my favorite breakfast spot. Or Congress.

But Customs has been busier now that it has merged with the Border Patrol and finds itself responsible for 2,000 miles of porous southern border. And besides, the Coast Guard has, in recent years, refined the so-called "airborne use of force" mission using a small squadron of MH-68 choppers based in Jacksonville, Florida. These nimble birds are ideal for chasing down drug smugglers' fast boats and positioning snipers to shoot out their engines so Coast Guard cutters can move in for an arrest. It was a small step for the Coast Guard to perform a similar mission using its standard HH-65 rescue choppers, targeting airplanes instead of boats. Details about the D.C. detachment are classified, but the choppers' presence is pretty obvious when they're flying right overhead.

Five years ago, armed Coast Guard helicopters were a rarity. But the service has beefed up since 9/11 to tackle a wider range of increasingly lethal threats, from smugglers to terrorists and even, while deployed alongside the Navy, waterborne insurgents. The future of warfare is looking more and more like policing on steroids. So the nation's coastal cops are becoming more like warriors every day.

I went flying with an HH-65 unit over Atlantic City this week. It was great fun. Check out my Flickr stream for pics.

--David Axe