Right,
The US KEY has NO buttons. They have two parts. The ignition part and the door entry part.
Basically they have married the two together in one key.
They have taken the transponder chip out if the key part, see the pic of the key broken in half. Then they have taken the door entry part and cut the alarm button part off. And just put it into the new flip key. They are the right size for the original entry fob part.
So now they have one flip key from two separate fobs.