https://en.wikipedia.org/wiki/Maritime_Drug_Law_Enforcement_Act

The United States has enforcement authority over any ship trying to smuggle illegal drugs into the US. Any vessel that isn’t registered to any particular nation is subject to seizure or destruction. The Royal Navy recognizes this law as well. They work closely with the US Navy in the region because of British Commonwealth countries. The US Navy and allies are the ones who enforce the concept of international waters.

For example, The CCP doesn’t recognize the Taiwan strait as international waters. But we do.

See also Economic Exclusion Zone (EEZ) and Air Defense Identification Zone (ADIZ)