SAN DIEGO (AP) — The U.S. and Mexican governments are sparring over immigration and trade, but the two countries are joining forces on the high seas like never before to go after drug smugglers.

A combined maritime operation that also involves Colombia is scheduled to start Sunday and marks an unparalleled level of cooperation between Mexico and the United States.

U.S. Coast Guard Adm. Paul F. Zukunft told The Associated Press the operation will start off South America's coast, where the flow of drugs is heaviest.

Experts say the two countries are working closer on security issues despite political tensions over President Donald Trump's stance on immigration and other cross-border issues.

The operation comes as the Coast Guard makes record seizures. But officials say the tiny service still only catches about 25 percent of the illicit shipments.