Development work on the CFM56 began before CFMI was formally created. While work proceeded smoothly, the international arrangement led to unique working conditions. For example, both companies had assembly lines, some engines were assembled and tested in the U.S. and others in France. Engines assembled in France were subject to the initially strict export agreement, which meant that GE's core was built in the U.S., then shipped to the Snecma plant in France where it was placed in a locked room into which even the President of Snecma was not allowed. The Snecma components (the fore and aft sections of the engine) were brought into the room, GE employees mounted them to the core, and then the assembled engine was taken out to be finished.