I've had a Vanguard IRA as a J-1, and now on an H1-B. They did tell me over the phone that I couldn't do it but some guy on a forum told me I should just go ahead and sign up as a resident, so I did. For the first couple months I was living in fear of being discovered by the Retirement Police but this year is the third time I fund it fully. If I wasn't eligible, I sure as hell hope that their back office checks would have figured it out by now.