Why Are 7,000 Marines and 46 Warships Going to Costa Rica?

Costa Rica ranks high in the international rankings set forth by that preeminant global body, the UN.

According to Scott Oliver at We Love Costa Rica.com:

On the 2nd July 2010 the Costa Rica Congress authorized the entry of 46 U.S. warships capable of carrying 200 helicopters and warplanes, plus 7,000 U.S. Marines "who may circulate the country in uniform without any restrictions", plus submarine killer ships to the Costa Rican coast for "anti-narcotics operations and humanitarian missions' between 1st July 2010 until 31st December 2010.

 Thing is, Costa Rica doesn't  have a huge drug problem compared to other Latin American countries.  It seems like a pretty lame pretext to me. Any ideas as to what's up with this?