What did the U. S. do in order to counter the Berlin Blockade?

The Truman Doctrine and the Marshall Plan

Explanation - "

Truman announced in a speech to Congress that the United States would be henceforth "support free people who are resisting attempted subjugation by armed minorities or by outside pressures," by giving them military aid."

In response to the Berlin Blockade the United States began a massive airlift off food, water, and medicine to the citizens of the besieged city. Supplies from American planes sustained over 2 million people in West Berlin.