Under current law, all male U.S. citizens are required to register with Selective Service within 30 days of their 18th birthday. In addition, foreign males between the ages of 18 and 25 living in the United States must register. This includes permanent residents (holders of Green Cards), refugees, asylees, dual citizens, and illegal immigrants.[2] Foreign males in the United States as lawful non-immigrants (international students, visitors, diplomats, etc.) are not required to register.
Source: Wikipedia
I believe at that time he claimed exemption to Columbia U. as an Indonesian citizen because of his adoption by Soetoro, without dual citizenship. Possibly he even claimed Kenyan birth at that time. Hence the dubious-looking selective service registration form that has been released.
The social security number would never have been a problem - there seems always to have been a sufficient paper trail of a Hawaiian birth for him (or his grandmother on his behalf) to apply for one.
My take is that he was born in Hawaii, lied about it sometimes to glamorize himself, and denied being a US citizen when it was convenient.
War with Iran was almost assured, and our generation was young enough to remember Vietnam. We knew people who went to Vietnam.
Millions of us signed up knowing we might get called within months. The dirt-bag in the white house hid behind his Indonesian and Kenyan passports. A real yellow bellied POS.