As for the US govt.--which works for Exxon, BP, etc.--it has always been weak because
1) Its military can't fight worth crap, as evidenced by its 8 year bungling in Iraq and continual bungling in Afghanistan against Third World adversaries w/crude weapons.
2) It has never in the last 50 years, under all administrations, stood up for democracy; rather, it only claims to do so when it's in the best interest of its corporate-backed or AIPAC-backed sponsors, and condemns all democracies that are detrimental to those interests, and the rest of the world knows it and therefore never trusts anything the US govt. says.
So, in a nutshell, Obama did not do anything to weaken the US or the US govt. because it has already been weakened by prior administrations beyond all hope. FYI, one can only weaken something that was strong to begin with.