Analyst's note:  Absolutely must read.  I've been asking for years now why we are buying material for our military related or primary infrastructure systems from foreign countries.  This has never made good sense.  Now the reason not to do it is clear. "....With this capability, China would be in a position to sabotage critical U.S. weapons systems and sensitive telecommunication  sites which would likely include intelligence or other systems used by defense contractors doing work on behalf of the U.S. government."  For additional perspective you will want to read 'Not so silent' war being waged against U.S. .... by China  It is really hard to recover from totally stupidity.

Chinese companies apparently have a covert capability to remotely access communications technology sold to the United States and other Western countries and could “disable a country’s telecommunications infrastructure before a military engagement,” according to former and current intelligence sources cited ina report in Joseph Farah’s G2 Bulletin.

The Chinese also have the ability to exploit networks “to enable China to continue to steal technology and trade secrets,” according to the open source intelligence company Lignet, which is comprised of former U.S. intelligence analysts.

[....]These parts don’t just come directly from China but also from suppliers in Britain and Canada who redirect Chinese products to U.S. defense contractors. [....]