Why did president Truman say that foreign aid was critically important?

Immediately following the end of WWII, in countries like Greece and Turkey, Great Britain announced they would stop financial and military support to the democratic govenments of these two countries. Stalin was supporting rebellions in these countries attempting to take over the governments with armed forces.

President Truman went to congress with a request for $400 million to aid each of these countries. In his speech to congress he addressed what he believed to be a threat from Russia to expand its communist government policies into many countries in that part of the world.

Truman stated the presence of communist regimes in this part of the world was a direct threat to peace and security of free people and the countries targeted by Stalin in this region and was therefor a threat to the United States.

Explanation:

With the Truman Doctrine, President Harry S. Truman established that the United States would provide political, military and economic assistance to all democratic nations under threat from external or internal authoritarian forces. The Truman Doctrine effectively reoriented U.S. foreign policy, away from its usual stance of withdrawal from regional conflicts not directly involving the United States, to one of possible intervention in far away conflicts.

the south did not want the federal laws to overrule the state laws.