WikiLeaks said on Saturday (01/08/2011) that U.S. investigators had gone to San Francisco, the headquarters of Twitter Inc. to ask for contact information, secret messages, and other data relating to Julian Assange and colleagues at WikiLeaks. Similarly, as quoted from Philly.com, Sunday (01/09/2011). And until now, the Twitter refuses to give a statement.
WikiLeaks also said that they suspect that other U.S. Internet companies have also been approached by the U.S. government, as part of the investigation.
U.S. authorities are examining the possibility to sue WikiLeaks along with their staff, related to some leakage of classified information to embarrass and damage the image of the U.S. government.