Turkish troops have been in northern Cyprus since 1974. The international community deems this to be an "occupation" of a sovereign state, but Turkey insists the measure is both legal and necessary.
Turkish and Greek Cypriot leaders are thrashing it out this week at Switzerland's Crans Montana resort in high-level negotiations to end 43 years of ethnic division in Cyprus.
The meetings – also attended by top representatives from the United Nations, the European Union, Greece, Turkey and the United Kingdom – are deemed by many to be the last chance to reunite the eastern Mediterranean island.
Cyprus was split into Turkish Cypriot-controlled northern and Greek Cypriot-controlled southern territories following a brief war in 1974, which saw Turkey intervene militarily following a Greek-inspired coup designed to annex Cyprus to Greece.
Today, Turkey still maintains some 35,000 troops in the island's breakaway north, and says that it will not withdraw its soldiers until a tangible agreement to reunite the island is reached.
This has proved to be a constant stumbling block in talks, with the Greek Cypriot side refusing to make any guarantees until the Turkish troops withdraw.
So why did Turkey intervene?
Turkey insists that its presence in Cyprus is in accordance with a treaty which grants it guarantor status that was signed in 1960 between the Republic of Cyprus, Turkey, Greece and the United Kingdom.
According to the treaty, Turkey, Greece and the United Kingdom all have the right to "consult together" regarding the independence, territorial integrity and security of Cyprus in the event of a collapse in the island's state of affairs as established and regulated by its constitution.
The treaty also grants the three guarantors the right to "take action with the sole aim of reestablishing the state of affairs" unilaterally if "common or concerted action may not prove possible."
By 1974, the state of affairs on the island had already withered after Turkish Cypriots were forced to boycott the joint government in 1963 when then-president Archbishop Makarios III failed to uphold the rights granted to them in the constitution.
But when a Greek military junta ousted Makarios on July 15, 1974, Turkey took unilateral action to end the violence, citing concerns over the safety of Turkish Cypriots on the island.
What happened next?
Turkey's intervention began on July 20, 1974 – five days after the coup. Makarios had already fled the island, and Nicos Sampson had taken his place as president.
The Turkish intervention saw the collapse of the Greek military regime in Cyprus as Turkish troops advanced southwards, having started their operation in the north of the island.
But initiatives undertaken by the international community resulted in the advance stalling, with 37 percent of the island remaining under Turkish control. The north became a safe haven for Turkish Cypriots, while most Greek Cypriots living in the north fled to the south.
A UN-controlled buffer zone and ceasefire line was established to divide the two sides.
Years of futile peace talks to bring about a solution commenced immediately, but in November 1983, the Turkish Cypriot side declared the independence of the Turkish Republic of Northern Cyprus (TRNC).
The TRNC was rejected the international community, which maintained that the Greek Cypriot administration the south was the legitimate authority of the island.
Turkey, on the other hand, does not recognise the Greek Cypriot administration, and instead argues that the Republic of Cyprus dissolved in 1974.
Will Turkey pull out of Cyprus?
The failure of the Turkish and the Greek Cypriots to reestablish the island's state of affairs through talks has made it impossible for Turkey to withdraw its troops.
Turkey has, however, supported peace efforts between the two sides which would ultimately lead to a Turkish withdrawal.
Ahead of the island's accession to the EU in 2004, Turkey encouraged Turkish Cypriots to vote in favour of reunification in a referendum in accordance with a plan presented by then-UN chief Kofi Annan. While Turkish Cypriots overwhelmingly backed the plan, the Greek Cypriot side rejected it.
Nonetheless, Turkey has consistently refused to pull out its troops until a satisfactory deal has been achieved. Even then, Turkey has indicated that it has no plans to give up its right as a guarantor.
The Greek Cypriot side, however, does not want any guarantors under a new peace deal.
At the moment, it seems that the talks in Crans Montana are deadlocked around this issue. Should the two sides fail to find a compromise, the talks, which are designed around a UN-endorsed plan to reunite Cyprus as a bizonal federation, could collapse.
As has been the case when previous plans failed, the status quo on the island is likely to prevail until a new plan is put forth. There is currently no word of what a new plan would look like, but with hopes for unification fading, there is an increasing probability that a future plan may be drawn up around separation.
It is also possible, however, that the two sides may agree to a revised guarantor treaty.
A revised treaty might curb the right of the guarantors to take action unilaterally, or limit guarantor status to a designated portion of the island.
Negotiators could likewise come up with a timeline that would oversee the gradual reduction of Turkish troops in Cyprus.
Whatever the outcome, the international community is piling on the pressure on the two sides to reach an agreement this week, with the UN threatening to withdraw its peacekeepers if a deal is not struck – perhaps at a time when they may be needed the most.
Author: Ertan Karpazli