HAMBANTOTA, Sri Lanka — Every time Sri Lanka’s president, Mahinda Rajapaksa, turned to his Chinese allies for loans and assistance with an ambitious port project, the answer was yes.

Yes, though feasibility studies said the port wouldn’t work. Yes, though other frequent lenders like India had refused. Yes, though Sri Lanka’s debt was ballooning rapidly under Mr. Rajapaksa.

Over years of construction and renegotiation with China Harbor Engineering Company, one of Beijing’s largest state-owned enterprises, the Hambantota Port Development Project distinguished itself mostly by failing, as predicted. With tens of thousands of ships passing by along one of the world’s busiest shipping lanes, the port drew only 34 ships in 2012.

And then the port became China’s.