Treaties must be ratified. The President cannot enter into any treaty all by his dictatorial little self.
But he CAN order that all government agencies under his control, including the ATF, act as though it were the law of the land.
Then why pray tell did George Bush bother to "unsign" the International Criminal Court Treaty? Hmmm???
Ever since the Vienna Convention on the Law of Treaties went into force, a signature is enough grounds for the government to begin to enforce it. Even though the Senate rejected it, it has been treated by the government as "customary international law."
Oh, and if you still feel comfy in that ignorance, realize this: Per Article II Section 2, Clause 2 of the Constitution, it only takes 34 Senators to ratify a treaty, "two thirds of the Senators present" presuming a quorum of 51. You can learn more about how that happened here.
Just who do you think will stop him? I have little reason to trust the Senate and the house has no real say other than budget, and they have shown their true self by letting the administration operate without a budget for four years.
We have no clue where the money is going or how much.