Case in point. Obama supports a UN treaty on what a US official terms "illicit arms trafficking and proliferation". At the same time, the US and ally Saudi Arabia are sending heavier arms into Syria. These shipments and their past interference in Syria violate the UN charter to which they solemnly pledged to adhere. The US is not alone in these and other violations in Syria and other countries.
If Washington routinely violates its own Constitution, it is to be expected that it can and will violate any agreement it makes. Hypocrites cannot lead on any issues, not when they have no credibility. They can exercise power, but they cannot lead.