I'll help answer your question of "how does this help?" He has given his constituents an idea of how things will be handled. He has also shown the rest of the world that threats will no longer lead to inaction.
Don is a man that makes things happen and does not mess around playing footsies with people/countries that could use a lesson on human diplomacy in regards to terrorism and the likes.
As scary as it may be, it definitely sent a message-for that, I think he did the right thing while keeping the focus on humanity.