You're talking about the obligations of the US Government. The US Government clearly only has the obligation to secure the rights of its own citizens.
nkoren is talking about the rights of the US Government. Just look at the language of the very first clause. All men are guaranteed these rights. It makes no mention of citizenship. That the US Government has the obligation to protect the rights of only US citizens does not mean that it has the right to violate the rights of non-US citizens. I don't buy the bullshit that the government can only protect my rights by violating the rights of others. That's small-minded thinking.
I agree with 4891 that nations act like criminal gangs. I seem to be one of very few who believe they shouldn't, though.