Saudi Arabia and Sep. 11

"A Lloyd's insurance syndicate has begun a landmark legal case against Saudi Arabia, accusing the kingdom of indirectly funding al-Qa'ida and demanding the repayment of £136m it paid out to victims of the 9/11 attacks.  The Brighton-based Lloyd's 3500 syndicate, which paid $215m compensation to companies and individuals involved, alleges that the oil-rich Middle Eastern superpower bears primary responsibility for the atrocity because al-Qa'ida was supported by banks and charities acting as "agents and alter egos" for the Saudi state."  I support the argument but I don't understand why the US government is not listed since Saudi Arabia and US both jointly supported the extremist fanatics in Afghanistan (from which emerged Al-Qa`idah).