In fact, it has happened and almost a century ago.

In 1918, the most devastating war the world had ever seen ended with the exile of German Kaiser Wilhelm II and the disintegration of the Austro-Hungarian Empire.

The peace settlement at Versailles in 1919 demonstrated a desire for revenge, imposing heavy and punitive reparations on Germany.

The roll of Olympians who perished was desperately long.

It included French 5000 metres silver medallist Jean Bouin, who died in the first few weeks, Australian swimming champion Cec Healy and Britain’s 400m victor Wyndham Halswelle.

International Olympic Committee (IOC) President Baron Pierre de Coubertin had enlisted in the French army and placed the organisation in the care of Swiss colleague Godefroy de Blonay for the duration.

As thoughts turned to re-establishing the Olympics in 1920, de Coubertin spoke of a "big problem", namely the participation of the Germans and their "Central Power" allies.

It had only been a few months since the last cannon shot. Common sense suggested it would hardly be wise for a German team to appear in the Olympic Stadium in Antwerp.

On the other hand, to ostracise any member country, even right after the conflict that had torn Europe asunder would create a rift in the Olympic constitution. "It might become a dangerous precedent," said de Coubertin.

It was not a view shared by all. Sir Theodore Cook, a leading figure in organising the 1908 Olympics in London, actually resigned his IOC membership during the War.

"It seemed to me that sport with Germany as a comrade had become impossible and that the Games without her could neither be called Olympic, nor described as open to the world," he said.

In the columns of The Field magazine, Cook told his readers: "If we are asked to compete against Germans, we should refuse."

In fact, invitations to take part at Antwerp 1920 were accepted by 29 nations including the United States, France, Italy, Denmark, The Netherlands, Sweden and Britain.

It was reported that athletes from Germany, Austria, Hungary , Turkey and Bulgaria "will not be allowed to take part in these Games".

The Olympic rules of the time did not mention excluding any team but as de Coubertin pointed out, the organising committee of the Games sent out the invitations, "according to the custom introduced in 1896".

It was hardly surprising that Belgians would not wish to invite the Germans so soon after the War.

"The Organising Committee is in control of distribution without the fundamental principle of universality having to suffer any direct infringement," mused de Coubertin.

Many competitors wore military uniform in Antwerp and wreaths were laid in remembrance of those who had died.

When Paris was chosen as host city for 1924, the question of German participation again came to the fore.

In Rome, Professor Franjo Bucar, President of the Yugoslav Olympic Committee "requested that the IOC clarify its position towards Germany".

Shortly before Paris 1924, the IOC welcomed two new German members but no athletes amongst the 3,072 competitors.  What de Coubertin had called a "simple solution" had again enabled the IOC to dodge the issue.

In fact, the Germans did not return until 1928 in Amsterdam.

Rehabilitation was completed in 1931 with the choice of Berlin as the 1936 host city with Garmisch Partenkirchen for the Winter Games, a decision made two years before the Nazis came to power.

A Second World War made it impossible for Games in 1940 or 1944, but even before the fighting ended, there were tentative soundings on 1948.

At that time the Olympic Charter provided for the expulsion of members who "have betrayed its interests or disregarded the laws of honour of good sense". It still did not include an explicit clause on excluding National Olympic Committees.

A concerned IOC Executive Committee member Lord Aberdare contacted his American colleague Avery Brundage: "I hope I may have your assurance that if Olympic Games are to be held somewhere in 1948, at least the Germans and Japanese will not be invited to compete," he wrote.

Acting IOC President Johannes Sigfrid Edstrom of Sweden had said: "My answer to the question of whether the Germans and the Japanese will be invited was that when enemy countries were recognised politically and commercially, they will no doubt be recognised athletically."

If the matter was raised at the first post-War executive meeting in London it was not minuted. Brundage later assured Sweden’s Clarence von Rosen that invitations would be sent only to countries "having National Olympic Committees (NOCs) which are accepted within the community of nations".

Edstrom noted "there is still considerable anti-German feeling". Although the Germans were keen to form an NOC, there was no hurry elsewhere.

Swiss Olympic official Francis- Marius Messerli wrote that Japan and Germany would not be invited to the 1948 Winter Games in St Moritz because "neither had a National Olympic Committee".

When London 1948 chairman Lord Burghley announced the invitations, Germany and Japan were not among them.

The Olympic regulations had again enabled exclusion without saying so in as many words.

"The IOC takes the view that recognition of a German Olympic Committee cannot take place until Germany has been formed by the Western states. German participation in 1948 should not therefore be possible," Edstrom told German IOC Member Duke Adolf Friedrich Zu Mecklenburg.

Even the ceremonial Olympic flag was not brought to London by representatives of Berlin, as required by the protocol of the time. Instead, it was carried by an officer in the Scots Guards.

One German did take an active part in London 1948. Prisoner of War Helmut Bantz helped coach the British gymnastics team, but German and Japanese Olympic teams did not return until 1952.

The most significant national ban was yet to come. 

South Africa’s apartheid system was established by the time an all-white team took part at Rome 1960, but the Olympic world was changing. Many African nations became independent and had support from the Soviet Bloc. 

The South Africans did not compete at Tokyo 1964 but many were frustrated by the lack of action under IOC President Brundage. Eventually, a fact-finding mission led by future President Lord Killanin was sent to the Republic.

At the time the Charter insisted that National Olympic Committees "must be completely independent and autonomous and in a position to resist all political, religious or commercial pressure"

No South African team took part at the 1968 Mexico City Games but it was not until the 1970 IOC Session in Amsterdam that a decision came. There had been violent protests during a Springbok rugby tour to Britain earlier in the year. The IOC Executive Board were fearful of a repetition if a South African team attended Munich 1972.

The matter was discussed under Item 23b of the agenda. The IOC Executive Board "recommended no invitation be sent to South Africa in any event until there was an improvement in the international climate".

The IOC Session heard submissions from Nigeria's Chief Abraham Ordia and the Congolese Jean-Claude Ganga, both then leading lights in African sport.

The IOC voted to "withdraw recognition" by 35 votes to 28 and South Africa were expelled and did not compete again until 1992. It was the longest Olympic ban ever imposed on a country.

As South Africa returned to the Olympic fold at Barcelona 1992, Yugoslavia faced exclusion after rising nationalism had erupted into a brutal civil war.

In May 1992, the United Nations (UN) banned all relations with Yugoslavia and UEFA followed suit. The Yugoslavs had qualified for the 1992 European Football Championships but were not allowed to play.

By this time, the IOC, hardened by a decade of boycotts, insisted they would not punish the athletes themselves. They told the UN they "could not accept a decision of this kind and in the teeth of considerable difficulties" held direct negotiations with the UN Security Council. Eventually an agreement was reached.

Though Yugoslavia did not appear, her athletes were permitted to participate as individuals.

The current Olympic Charter describes the IOC as the "supreme authority and leadership" of the Olympic Movement. A full chapter is now devoted to "Measures and Sanctions, Disciplinary Procedures and Dispute resolution".

The Executive Board can recommend the suspension of any National Olympic Committee for "any violation of the Olympic Charter".

This act removes the right "to participate in any activity connected with the Olympic Movement". All financial assistance from the IOC and Olympic Solidarity is also withheld. The flag of the nation concerned is not flown at any Olympic events, though athletes are permitted to compete as Individual Olympic Participants under the Olympic flag.

In December 2012, the IOC "expressed severe concerns about government interference in the upcoming election process", with regards to the Indian Olympic Association.

Suspension followed and the Indian flag was not seen at the Sochi 2014 Opening Ceremony. The small Indian contingent competed as individual Olympic participants. When a settlement was reached, their flag was raised in the Athletes’ Village midway through the Games.

In the last decade, Kuwait have been suspended, reinstated, and then banned again in the words of the IOC "to protect the Olympic movement in Kuwait from undue government interference".

Most recently, a provisional suspension was also imposed on the Brazilian Olympic Committee and Rio 2016 President Carlos Nuzman was stripped of his IOC honorary membership as investigations into corruption continue.

Only Russian track and field athletes were banned from Rio 2016, but former World Anti-Doping chairman Richard Pound said the decision not to ban the entire Russian team was "an opportunity lost, a huge loss of moral authority by the IOC".

Pound is now the doyen - most senior member of the IOC - and this week warned IOC President Thomas Bach not to "stuff it up" when making the decision for Pyeongchang 2018. 

If Russia are banned completely from Pyeongchang 2018, in sporting terms, it would have the most significant impact of all.