Oh FFS.
They cheer, but they don't know what they're cheering for.
The UN treaty regulates nothing but small arms shipments to rogue nations. It has nothing to do with, for example, importing legal sporting arms from a European manufacturer such as HK or Walther to the US. National laws are explicitly recognized as governing their own internal affairs. The treaty prevents exporting of small arms to rebel groups, pirates and drug gangs in places like Somalia or Sri Lanka or Central America. Remember how Trump's against people fleeing Central America to try to get asylum here? He just announced he's going to help make their countries even more unlivable and increase the number of refugees.
This is why I'm a gun owner, but emphatically NOT a member of the NRA. They're knee-jerking morons who assume any law relating to guns is a covert plot to disarm us all by the evil gun-grabbing UN and the bleeding-heart Democrats.