It has been public knowledge for a long time that the U.S. government has suppressed thousands of patents over many years.
What is not widely known is that there is a secret system to delay and withhold the approval of patents. This system is known as the Sensitive Application Warning System (SAWS). This has been known since March 2006.
Recently, there has been a new 50 page document released that actually shows the full range and reach of this system and it is shocking!
Go here for more details: https://www.yahoo.com/tech/the-u-s-government-has-a-secret-system-for-104249688314.html