Sorry for my poor/wrong usage of the word "citizen", I meant resident with SSN, US address, bank account, ID card, US credit/debit card etc.. as stated in the FAQ [1]. So definitely you shouldn't be able to launch a project by residing in another country and just "faking" a US address using something like those shipping forwarding services used to buy stuff in the USA

[1] http://www.kickstarter.com/help/faq/creator+questions