[defrost]

Hell of a name for an operation launched to appease a request by the Mexican Government to return labourers to Mexico.

https://en.wikipedia.org/wiki/Operation_Wetback

If I'm reading that correctly the US wanted the labour, and the Mexican Government wanted the US to enforce stricter control:

  Pressure from Mexican agribusiness owners to return laborers from the United States to Mexico prompted increased action by the Mexican government.

  The labor problems caused crops to rot in Mexican fields because so many laborers had crossed into the U.S. Meanwhile, American agriculture, which was also transitioning to large-scale farms and agribusinesses, continued to recruit illegal Mexican laborers to fulfill its expanding labor requirements.

It would seem that Eisenhower wanted cheap Mexican labour and the Dual US/Mexico programs that provided it - the enforcement to cap the numbers was a condition imposed by Mexico to keep the agricultural labour agreements in place.