Thailand's ambitious plan for a land bridge, connecting the Gulf and Andaman Seas, has resurfaced due to geopolitical tensions. While proponents view it as vital for global trade, critics question its high cost and environmental impact.

Thailand’s vision for a land bridge splits opinion: some see it as a crucial new Asian trade route for a global economy held hostage by geography, while others view it as an expensive and environmentally ruinous distraction for a kingdom with plenty already on its plate. But to its backers, the proposed road and rail corridor, bookended by ports on the Gulf of Thailand and another 90km (56 miles) away on the Andaman Sea, to bypass a vital chokepoint, has never felt more urgent. Iran’s virtual...