The United States and the Soviet Union had very different ideologies and views of security. The Soviet Union wanted buffer states to protect its borders and hoped to spread communism to other countries to assist in that aim. The United States wanted to protect and defend democracy and, according to the Truman Doctrine, adopted a policy of containment. Both countries mistrusted each other, and each suspected that the other was trying to take over the world. This affected their relations with each other and their relationships with other nations.