From the given sentence, extract the phrase (often noun or verb) that carries the given relationship. The generated phrase should be present in the sentence.

Given Relationship: 'invade', Sentence: 'When the Soviets invaded Afghanistan , America needed to stop the communists on that front and by befriending Pakistan , they thought they had gained a trustworthy ally and an " American-friendly " base as a counterweight against the Soviet sphere of influence in the Southeast .'
invaded