People wave Russian flags in Lenin Square to celebrate the preliminary results of the Crimean Referendum, in Simferopol, Crimea.

People wave Russian flags in Lenin Square to celebrate the preliminary results of the Crimean Referendum, in Simferopol, Crimea. Photo: Kate Geraghty

Crimea held a controversial referendum on Sunday to decide whether to join the Russian Federation. Russian exit polls indicate that a big majority have voted ''yes''.

The disputed ballot follows the unseating of Viktor Yanukovich as Ukrainian president last month, the subsequent incursion of additional Russian troops into Crimea, and a vote earlier this month by Crimea MPs to become part of Russia.

According to British Foreign Secretary William Hague, the situation represents "the biggest crisis in Europe in the 21st century".

The US will not recognise the outcome of the vote, but has not yet revealed what specific actions it will take in coming days, including the nature of sanctions. The speed with which the US and other countries moves here may depend on the degree to which Russia demonstrates in coming days any plans to formally annex Crimea, or pour more troops into the region.

In seeking to frame Russia's actions in Crimea (which was annexed into Ukraine in 1956 by Soviet leader Nikita Khruschev), various historical analogies with Nazi Germany have been made, including earlier this month by former US secretary of state Hillary Clinton. The use of analogies by politicians in international crises is commonplace. In the complexity and uncertainty of fast-moving day-to-day events, policymakers often seek to draw what they perceive as lessons of the past in seeking to guide and provide rationales for their actions.

For much of the period since the 1970s, for instance, many US officials were fearful of ''another Vietnam'', referring to the disastrous US intervention in that country. This tended to reduce willingness to deploy US military force internationally unless any action (such as the 1991 Gulf War) had clear, attainable objectives that could swiftly be achieved with a minimum of casualties.

The Vietnam debacle also became a frame of reference when the US-led intervention in Iraq faltered after 2003. This was despite the fact that the two experiences (Iraq and Vietnam) were dissimilar in many respects, including the nature of the insurgencies and US objectives in each country.

But the most widely used historical analogy is that of Munich and Nazi Germany. The widely seen implication for foreign affairs of the 1938 British-French agreement with Adolf Hitler is that appeasement with aggressors doesn't work.

Numerous politicians claim to have been influenced by Munich. These range from George W.Bush during the ''war on terror'', Margaret Thatcher over the Falklands conflict, Lyndon Johnson over Vietnam, and Anthony Eden and Guy Mollet during the Suez crisis.

While military action appears to have been ruled out by Western policymakers in Ukraine, the fact that Munich is informing thinking of some is reflected in Clinton's comments. She noted "the claims by President Putin and other Russians that they had to go into Crimea and maybe further into eastern Ukraine because they had to protect the Russian minorities, this is reminiscent of claims that were made back in the 1930s when Germany under the Nazis kept talking about how they had to protect German minorities in Poland and Czechoslovakia and elsewhere throughout Europe. I just want everybody to have a little historic perspective.''

While some see strong similarities between recent events in Ukraine and Nazi Germany's expansionism, the fact remains that use of analogies can be fraught with difficulty for policymakers. On a fundamental level, for instance, not all military actions end up like Vietnam, while not all diplomatic agreements turn out like Munich.

As history shows, there is a danger that policymakers misinterpret past crises just as frequently as they learn the right lessons. For instance, Suez and Vietnam underscore how Munich was used to guide or justify major foreign policy blunders by the US, Britain and France in the 1950s and 1960s.

Another example is John Kennedy during the Cuban missile crisis, who was influenced by Barbara Tuchman's The Guns of August , which argued that the First World War started as a result of miscalculation from all sides.

Kennedy believed the events of October 1962 were reminiscent of the lead-up to that conflict and wisely sought to deploy a range of diplomatic options, overruling military advisers urging a quick strike on Cuba.

However, an increasing number of academics believe Germany actively sought war, and that Tuchman's thesis is wrong.

In this sense, it has been argued that Kennedy's actions (which were prudent in the context of Cuba, and may have saved the world from nuclear war) were based on a misreading of history.

In the case of Ukraine, Munich is by no means the only historical lens through which to interpret what is happening. And, even if it were, there are clear differences between the 1930s and today, including the interdependence of the global economy, wider dissimilarities in the global balance of power, and that Russia has an extensive stockpile of nuclear weapons.

In the unpredictability and tension of the current moment, it is certainly the case that, like Kennedy in 1962, calm, clear and careful decision-making is now needed by Western (and indeed Ukrainian) politicians as they think through the array of non-military options they have at their disposal, including sanctions.

History can provide an especially useful framework in addressing similar or identical policy challenges, but to avoid potentially major misjudgment, policymakers need to pay attention to the significant differences between the past and present.

Andrew Hammond is a former special adviser to the British government.