The end of the Cold War was brought on by economic distress in the Soviet Union due to high defense spending and economic inefficiencies. Gorbachev was willing to negotiate with Reagan, which led to a thaw between the two nations. This openness in negotiation led to an influx of more Western culture into Eastern Europe. The end of the Cold War led to the reunification of Germany—the fall of the Berlin Wall remains one of the most iconic moments from this era. The reunification of Germany coincides with the formation of a free and independent Poland as well as the removal of many Soviet puppet leaders in Eastern Europe. Many separatist states left the Soviet Union, most notably the Baltic states and Ukraine. The end of the Cold War brought more open reforms and liberal policies in Russia, though the nation would be hit by economic hardship during much of the 1990s as it transitioned to capitalism.
After the end of the Cold War, American foreign policy turned towards the Middle East. The United States led a coalition of nations that pushed Saddam Hussein out of Kuwait in Operation Desert Storm. The end of the Cold War saw the US defending itself from non-state actors who could get access to chemical, nuclear, and biological weapons of mass destruction. This search for terrorists has led to the global war on terror, which has led to US interventions in Afghanistan, Iraq, and Syria. The US has also used sanctions more than direct threats of action against North Korea and Iran to curb their nuclear programs. The US's relationship with former Cold War adversaries such as Russia and China has become tense recently as the US considers these nations as potential threats to their neighbors.
There were several events that led to the end of the Cold War. The Soviet government became more open to negotiations under Gorbachev. Independence movements in Poland, the Baltic states, and Ukraine also led to the disintegration of the USSR. The fall of the Berlin Wall in 1989 also played a role—this was probably the greatest symbol of the end of the Cold War as its demolition was televised.
The Soviet Union had struggled for a long time before it's actual collapse. The Soviet economy was struggling. The nation overspent on its military in order to keep up with Reagan-era defense spending in the United States. The Soviet Union also fought a long unsuccessful war in Afghanistan. All of these factors led to dissatisfaction with the regime.
The end of the Cold War led to brief euphoria in the United States as the fall of the Soviet Union demonstrated to many the superiority of the American way of life; however, this euphoria was short-lived. Instead of facing one nation with nuclear capability, the United States now turned its attention to non-state actors who could access nuclear weapons on the black market. The United States looked to shore up its Middle Eastern interests by initially siding with Iraq in a war with Iran but later fighting Iraq after its invasion of Kuwait. The United States was also concerned about the rise of China as a commercial competitor. Within a decade of the end of the Cold War, the United States was also concerned about the rise of a new nationalistic Russia. While the "missile gap" is not the foreign policy issue that it was under the Kennedy and Nixon administrations, the United States is not as secure as it would have hoped after the end of the Cold War. Instead of two superpowers, the United States is the sole superpower in the world, but it has commercial rivals and it is under constant threats from non-state actors who are harder to attack than traditional enemies. These non-state actors such as ISIS and Hamas are the current foreign policy scare that the United States faces in the post-Cold War world.