Why was the U. S. joining NATO unprecedented in this country’s history?

NATO, or the North Atlantic Treaty Organization was established to protect the western European states and the Democratic system of governance against the rising influence from the Soviet Union and the communism.

USA was the leading member and one of the founding members of the NATO. This, effectively made the USA the leader of the "free world" and gave them the upper hand against the Soviet influence in Europe and out of the Europe.

Moreover, the combined military strength of the NATO made in the most powerful military organization in the world.

Explanation:

the option which was not a function of missionaries in the northwest was the first one - they established posts for trading furs and other goods.

missionaries were sent around the world to spread religion and their knowledge and others - they were not merchants who sold furs and other goods.