I'd put my money on the C_A & DEA.
Think of all the Chinese that have been brought in, legally, through H1B visas. They're second only to India and most of these are for STEM jobs that don't require a BS degree.
http://www.pewresearch.org/fact-tank/2017/04/27/key-facts-about-the-u-s-h-1b-visa-program/
This is an equal opportunity exploit from both sides of the isle. Businesses want the cheap labor and politicians that support increasing H1B surely reap the benefits to their reelection funds.