A recent breach of the US Treasury yielded access to Secretary Janet Yellen's computer along with those of two of her lieutenants, according to inside sources speaking to Bloomberg News reporters.

Chinese hackers accessed over 400 computers and over 3,000 unclassified files when they infiltrated the U.S. Treasury.

The US has issued sanctions against an individual and a company involved in recent high-profile compromises of government officials by Chinese state-affiliated hackers