The Marshall plan played a key role in the creation of NATO.
The Marshall Plan was created with the objective of helping european industries and infrastructure recover after the destrucion of WWII, as well as lower trade barriers between european countries and strenghten commercial relations with the United States, which was of mutual interest of both sides.
This cooperation was later strenghtened by the creation of NATO, a military alliance, where countries from Europe and North America collectively protect each other from the Soviet Union.