For more than four decades, talks for a reunified Cyprus, back on the table since May, have failed to come up with a power-sharing formula for its Greek and Turkish Cypriots.

US Secretary of State John Kerry visits Cyprus on Thursday in a bid to boost the talks, which have also struggled with issues inherited from the 1974 invasion: lost homes, Turkish soldiers still deployed in the north and landmines on the Green Line dividing the island.

- Property -

During the Turkish invasion, some 200,000 people fled in a population exchange, Greek Cypriots to the south and Turkish Cypriots to the north, abandoning their belongings, homes and land.

In the north, many Greek Cypriot properties are now occupied by Turkish Cypriots, Turkish settlers and even foreigners including Britons after controversial purchases.

In the south, the government has assigned some former Turkish Cypriot homes to Greek Cypriot refugees.

The island's main Larnaca airport and refugee housing were built on land belonging to Turkish Cypriots.

Greek Cypriots who have lost hope of retrieving their property in the north are increasingly turning to a Turkish commission to compensate them.

But this is discouraged by the Greek Cypriot authorities who view it as rightful owners giving in and selling their property cheap.

- Landmines -

The United Nations in 2010 said it had removed landmines in almost all of the island's buffer zone.

But a lack of detailed maps showing the zones where landmines were planted before 1974 has prevented the UN from clearing thousands of landmines in the rest of the island.

In May, the Greek Cypriots handed over a map of 28 minefields that UN experts are examining.

- Missing persons -

In 2006, a bicommunal committee supported by the United Nations started to excavate the remains of people who went missing in Cyprus during 1963-1964 inter-communal violence and the 1974 invasion.

Of the 2,001 persons officially missing, 1,000 have been exhumed, of which half have been identified and their remains returned to their families.

But over 250 possible graves remain untouched.

In a breakthrough move, Ankara agreed in early November to allow access to possible mass graves in military zones in northern Cyprus.

- Soldiers and settlers -

The Republic of Cyprus estimates that more than 160,000 settlers from Turkey's poorest regions live on the island.

A 2011 census by the Turkish Cypriot authorities showed that of 286,000 inhabitants in the north, 118,000 (40 percent) are Turkish expats, including 38,000 (13 percent) granted Turkish Cypriot "nationality".

But Ankara has also deployed some 30,000 Turkish troops on the island, according to Turkish Cypriot authorities.

Even some Turkish Cypriots object to their presence, which is seen as a major obstacle to reunification.

- Ghost town -

In 1974, when Greek Cypriots fled the seaside resort of Varosha, Turkey's army cordoned off its affluent homes and hotels with barbed wire.

The island's Saint-Tropez became a ghost town, its memory haunting some 40,000 former residents.

In retaliation for the Turkish occupation, the Republic of Cyprus pressed for an international embargo on the self-proclaimed Turkish Republic of Northern Cyprus, recognised only by Ankara.

Direct international trade with northern Cyprus, ships docking in Famagusta port and planes landing at Ercan airport are banned.

Passengers and goods instead have to transit via Turkey, which hampers tourism and economic activity in the north.

Turkish Cypriot leader Mustafa Akinci in May renewed the offer of returning Varosha in exchange for international access to the port and airport.