A constructivism emphasis on history would suggest that past relationships with our allies are at work in our country's current views of the rest of the world. Our prior experiences also shape our view of nations with which we do not have friendly relations.
Specifically, constructivism is a theoretical lens in sociopolitical thought that argues that we construct the realities in which we live. Constructivism says that knowledge is shaped by our experiences and interactions with the world. Our opinions and bases of knowledge are not a reflection of some external objective reality. The information we process is influenced by our biases and backgrounds.
This theory thus assumes that human understanding and sociopolitical and scientific views evolve and change over time. As a result, our relationships to others are also flexible and changeable. In history, our views of the world have been shaped by past relationships to other nations and the commonly shared narratives we have about the world around us. Therefore, it is not surprising that we choose allies whom we understand because we feel that there are similarities in culture, language, or other critical factors between our nations.
In other words, constructivists believe that our "allies" and "enemies" are constructed and that we create these relationships based on our prior experiences and relationships. Alexander Wendt's example of nuclear weapon threats provides an illustration. He explains that 500 British nuclear weapons appear less threatening to the US than five North Korean nuclear weapons because of our relationships with the respective countries. Everything depends on social context: our relations with North Korea are much worse than those with the UK. Our identities and prior experiences shape everything about our foreign policy.
Therefore, we must look at what historical factors have been important in shaping US identity in order to understand our relationship to other nations. Economic and cultural factors are at play here. The US emerged victorious after WWII, leading it to become the world's superpower. As a developed nation, the US identifies itself with other developed nations. Likewise, as a country with a strong Anglo-Saxon Protestant background, we identify with similar countries. Other countries that are different from the US culturally, like the Soviet Union in the Cold War and China today, appear as threats because we perceive them as being different. For this reason, Constructivist historians view the Cold War as constructed and not truly a function of a real material danger.