SEOUL, South Korea — As tensions between Tokyo and Seoul have surged in recent months, South Koreans have shown their anger with their wallets. Japanese beer is going unsold. Shoppers are avoiding Uniqlo. An animated Japanese children’s movie called “Butt Detective,” whose protagonist has a predictably posterior-shaped head, bombed in South Korean theaters.

On Wednesday, Japan widened the wedge between the two Asian economic powerhouses even further. It formally removed South Korea from a “white list” of countries to which it extends preferential trade status.

But it will take more than new rules and consumer boycotts to drive apart the two American allies, at least when it comes to business. The two countries have become deeply intertwined over the decades, with a trade relationship now worth about $85 billion a year. Japan in particular holds considerable power as a main supplier of essential raw materials and components to South Korea’s high-tech economic machine.

Until that changes, a process that could take many years, the two countries have little choice but to stick together. Any serious attempt to break trade ties “would be a disaster,” said Rory Green, an economist specializing in South Korea and China at the London-based analyst TS Lombard.