Verisign manages the registry and backend services for .com, .net, .name, .cc, .tv, .jobs and .edu (even though .cc and .tv aren't American TLDs). Other American companies run most of the other generic TLDs as well, including .org. Thus, they are all susceptible to US court orders to disable a domain.
Even if you register a TLD operated outside the US, be careful which registrar you choose to do so at. GoDaddy, a US company, is the #1 registrar worldwide, and has many times taken control of domains at US government request even when not legally obligated to.
