US, July 12 -- Cuba has spent decades presenting tourism as the economic showcase of its socialist system: a source of foreign currency, employment, and international engagement that could operate without requiring the country to surrender political control.

That model is now approaching its limits.

Hotels stand partly empty. International airlines have suspended or reduced services. Cruise terminals remain largely unused. Electricity shortages disrupt resorts as well as Cuban homes, while shortages of fuel, food, and imported supplies have made it increasingly difficult to deliver the standard of service expected by international travelers.

The collapse has been dramatic. Cuba received about 4.7 million international visitors in 2018...