Nope, cannot get Supplemental Security Income (SSI) in any foreign country (outside the USA), but getting Retirement Social Security (RSDI) anywhere in the world as an U.S. citizen is no problem
I was just about to comment on being some of the first to cross the new Friendship Bridge to be opened at Beung Kan–Paksan. As a side note, I have also crossed many of the Lao–Thai borders and find them quite fine and generally easy to cross....