The U.S. doesn't have the ships and surveillance capabilities to go after the illegal drugs flowing into the U.S. from Latin America, the top military commander for the region told senators Thursday, adding that the lack of resources means he has to "sit and watch it go by."

Gen. John Kelly told the Senate Armed Services Committee that he is able to get about 20 percent of the drugs leaving Colombia for the U.S., but the rest gets through.

Aided by surveillance planes, radar, human intelligence capabilities and other assets, Kelly said he has "very good clarity" on the drug traffickers who are moving the drugs out of Colombia and through the Caribbean Sea.

But much of the time, he said, "I simply sit and watch it go by. And because of service cuts, I don't expect to get any immediate relief in terms of assets to work with in this region of the world."

Kelly, who heads U.S. Southern Command, said he would be able to interdict more drugs if he had 16 ships that could be used as the base for helicopters. Generally, law enforcement officials use the helicopters to quickly go after traffickers operating small boats, forcing them to stop and surrender. Currently, Kelly said he has one U.S. Navy ship and two Coast Guard vessels that can be used for the drug operations.

Kelly added that he has seen an increase in the amount of drugs that are being moved through the Dominican Republic and Puerto Rico. The traffic through Puerto Rico is a particular problem, he said, because there are no U.S. Customs restrictions so packages can be sent easily through the mail.

— The Associated Press