My apologies for the tardy response. Funding is obviously an important aspect to growing a business anywhere in the world but even more so in the US. I would however note the implications for securing funding in the US. First off, US funders usually want to see that a foreign company has received some form of seed/initial funding from the home market as a sign of credibility. Basically, "If you cannot get funding in your home market, why should we fund you?"
Additionally, at least on the West Coast, VCs and Angels do not simply want to be a source of cash but a voice and influence on the business. They will likely want to take partial ownership and guide the direction of the business accordingly. Finally, because of the desire to be involved with company decisions once funded, most VCs will require that a portion of the executive team be located nearby, creating a separation from the HQ.
Depending on the size of investment that you seek, I would recommend looking into smaller pitch events and organizations where specilsed VC and Angel representatives may be present with seed funding objectives. Please see the resources below:
Keiretsu Forum: http://www.keiretsuforum.com/frontend/index.aspx
Plug and Play Tech Center: http://www.plugandplaytechcenter.com/
These are just a few resources but I would be happy to offer more if desired.
UKTI San Francisco