I can try and answer part of the question for you, but it is a massive subject.

Sub-Question: To what extent did US foreign policy under Ronald Reagan bring about the end of the Cold War?

The collapse of Soviet power and the subsequent ending of the Cold War came about almost immediatly after the eight year term of the ‘most anti-communist president in American history’, who exerted the greatest amount of pressure possible on the Soviet Union in almost every conceivable way. Crucially Reagan’s administration undermined the Soviet economy by diminishing its ability to import vital technologies and export its energy resources. Furthermore this served to increase the strain the Soviet Union already faced supporting large military and international commitments. However Reagan’s foreign policies were merely a contributing factor to the Soviet collapse, as the Soviet economy would have failed to produce growth and sustain existing military commitment’s despite Regan’s choices. The Cold War did not end because the Reagan administration outstripped the Soviet’s in military spending, nor because it undermined Soviet third world allies, and not even because it scared them with their plans for SDI. It ended because the Soviet economy was incapable of producing growth, and Gorbachev was determined to reform the Soviet Union. Therefore US foreign policy under Ronald Reagan did contribute slightly to the end of the Cold War, but only to a small extent.

Economic measures taken by the Reagan administration against the Soviet Union were perhaps more effective. Undermining the USSR economically could potentially bring about a Soviet collapse or retreat in three key ways. Firstly it could threaten the Soviet ‘ability to match the west militarily’. Secondly it could reduce the confidence of Soviet elites that their social system could prevail, or at least rival the West. Finally a weakened Soviet economy could also ‘weaken Soviet citizens’ attachment to that system’. The Reagan administration embarked thus on a process of ‘Economic warfare’ with the Soviets, attempting to undermine them at nearly every opportunity. An area in which they were particularly effective in doing this was in high technology goods, which the Soviet’s imported from the West in order to make up for their major technological shortcomings. Reagan attempted to reduce or prevent ‘western exports that were helping Moscow stay competitive’. In order to achieve this Reagan had the ‘Senior Interagency Group on Transfer of Strategic Technology’ (SIG-STS) set up in 1983. It was tasked with reducing Soviet technological acquisitions from the west by working with CoCom (Coordinating Committee on Multilateral Export Controls), to ban the export of certain technological goods from CoCom members to the Soviets or other Warsaw Pact countries. It was relatively successful, as sales of high technology products to the Soviets in 1983 were 82% lower than they had been in 1975. Customs controls on such exports were tightened and investigations stepped up, leading to the seizure of 1,400 shipments of ‘critical technologies which helped sustain sectors of Soviet Industry’.

The Reagan administration also sought to undermine the Soviet Economy by preventing the expansion of Soviet sales of oil and natural gas to Western Europe, which the Soviet Economy had begun to rely on to earn it foreign currency and subsidise inefficient domestic industry. The US therefore opposed the construction of the ‘Druzhba’ pipeline which allowed mass Soviet gas exports to Western Europe, but unfortunately for the Reagan administration this opposition failed to convince its European partners to reject the plan and the pipeline went ahead in 1982. However American officials managed to force an IEA (International Energy Agency) agreement in 1983 capping European energy imports from the Soviet Union at 30% of total European energy demand, which was later formalised at the G7 summit at Williamsburg in May 1983. This was a great blow against the Soviets because it prevented a massive expansion of Soviet energy exports to Western Europe. Had This IEA agreement not been put in place then it would have conferred two significant advantages on the Soviets. Firstly increased gas and oil exports could have helped sustain the Soviet economy, as sales of these accounted for far over half of foreign currency earnings and had become a vital part of the Soviet economy, receiving over 39% of total Soviet Industrial investment in the 1980s. Secondly it would have given the Soviets valuable diplomatic leverage when dealing Western European countries as they could threaten to cut off oil or gas supplies at crucial moments. Historians which advocate the view that the Reagan administration’s foreign policies brought about the end of the Cold War put forward a simple narrative: That the US, via military build-up, technological development and economic warfare, essentially demonstrated US superiority categorically, and that in the face of that clear superiority the Soviet Union gave up, seeing that it could never mount a successful challenge, and thus confined itself to the ‘ash heap of history’. However history shows us that states do not behave in such a fashion. For example North Korea cannot hope to compete with the US in any field, and yet it does not give up in the face of obvious US superiority. Therefore Reagan’s foreign policy cannot possibly fully explain the end of the Cold War. What truly brought about the end of ‘nearly 50 years of confrontation in just 5’ was indeed the work of a visionary statesman, but it was Gorbachev, not Reagan.

Foreign policy under the Reagan administration did seek to undermine the Soviet Union, and was occasionally successful in doing so, although this was probably not done out of a visionary plan to bring about the end of the cold war by defeating the USSR as several right wing historians have retrospectively made out. In the military field much is often made of Reagan’s massive military build-up, and SDI program, which is often postulated as what bankrupted the Soviets because they attempted to keep up with US arms spending and research but could not. However there is relatively little evidence for this, and while SDI did certainly seem to scare the Soviets and thus was perhaps effective in bringing about the end of the Cold War, the same is not true for the military build-up. This is because Soviet military spending statistics show that the US military spending increases do not solicit Soviet increases, thus refuting the argument that it forced the Soviets into further spending which subsequently bankrupted them. Nevertheless the Reagan administration was somewhat successful in undermining the Soviet economy; by denying it the technological imports it needed to sustain its economy whist restricting its ability to earn foreign currency via energy exports it significantly weakened the economy helping bring forward the collapse of Soviet power making the end of the Cold War possible. Therefore overall the foreign policies of the Reagan administration did, to a small extent, contribute to the ending of the Cold War. EDIT: Paragraphed horrifically massive block of text