The U.S. Coast Guard is committing itself to a 50% increase in manpower in the Caribbean and Central and South American waters, to help allies wracked by drug violence and guard seaways that could bring something worse than drugs to the U.S. mainland.

Commandant Paul F. Zukunft is taking a “calculated risk” to stretch Coast Guard resources even further “because he felt a need to promote security” on the U.S. southern sea frontier and for its neighbors, Vice Adm. Charles D. Michel said at hearing of the House Coast Guard and Maritime Transportation Subcommittee Tuesday.

Cocaine seizures are up this year, now over 83 MT compared to 91 MT for all of 2014, Michel, the Coast Guard deputy commandant for operations, told subcommittee members. Based on the best estimates of U.S. law enforcement and intelligence planners, the Coast Guard is intercepting perhaps 10% of the Western Hemisphere’s cocaine production, he said.

Subcommittee chairman Rep. Duncan Hunter, R-Calif., has been holding hearings with testimony from Coast Guard officials as part of the run-up for votes on appropriations. Hunter and other committee members have pressed for increases in the Coast Guard’s recapitalization budget for new ships, which has slowed with budget restraints the last five years.

The Coast Guard and U.S. Southern Command are up against “transnational criminal organizations” that are sophisticated and fielding new, asymmetric tactics and technology to evade U.S. forces, Michel and SOUTHCOM director of operations Rear Adm. Karl L. Schultz told the committee.

While smugglers still use high-powered “go-fast boats” for 80% of their maritime deliveries, they are stepping up use of self-propelled semisubmersible boats, with the latest one intercepted by the Coast Guard Tuesday morning, Michel said.

That came days after the Coast Guard unloaded a $13.7 million shipment of cocaine and marijuana recently seized from surface boats. But it is the submersibles that clearly alarm top officials.

With payloads of five to seven tons and a range up to 4,000 miles, the boats could be just as capable of carrying a weapon to U.S. shores, Michel said. That worry was renewed when Colombian forces discovered a true submarine with snorkel technology under construction in a clandestine shipyard. That vessel could have carried enough fuel to go non-stop to Los Angeles, Michel said.

Committee member Rep. Mark Sanford, R-S.C., asked if the $25 billion spent annually on anti-drug efforts is really working. Michel insisted it has, recalling his duty in the 1980s chasing “cocaine cowboys” in go-fast boats straight into Miami’s harbor.

“I can tell you it’s a long way from those days,” Michel said. “There are a lot of them, they’re still out there, they’re in Central America.”

The U.S. has an obligation to fight them at sea and nearshore waters, Michel and Schultz said.