Geneva ? The United States and the European Union entered Friday into what promises to be another politically sensitive trade dispute – only this time they find themselves on the same side.

While the two bicker about who was to blame for the impasse that scuttled global free trade talks, they are now joining with Canada in a World Trade Organization complaint about China’s tariffs on the import of foreign auto parts.

The dispute marks the first time the Western allies have teamed to seek a formal WTO investigation in a trade spat with China, and the issue will be included on the agenda when the organization’s settlement body meets later this month.