Turkey has been ordered to pay Cyprus €90 million (£73.3 million) in compensation for its 1974 invasion of the island.
In its largest ever judgement, the European Court of Human Rights (ECHR) said the passing of almost 40 years did not erase Turkey's responsibility for the ensuing conflict and continuing division of Cyprus.
The court ruled that the Turkish government must pay €30 million in damages to relatives of those missing in military operations and €60 million for “the enclaved Greek-Cypriot residents" of the Karpas peninsula.”
The Karpas peninsula in the northernmost tip of the breakaway Turkish part of the island is still home to hundreds of Greek Cypriots.
Only Turkey recognizes the Turkish Republic of Northern Cyprus that was proclaimed there.
Turkish forces were accused of ethnic cleansing after thousands of Greek residents were forced from their homes and replaced with Turks from the mainland.
Atrocities and massacres were alleged by both sides and more than 100,000 people became refugees during the invasion.
The invasion was sparked by a Greek military coup in July 1974, when supporters of union with the country took control.
The Greek military Junta collapsed and there was a second invasion by Turkey taking more than a third of Cyprus in August.
In Turkey, the events are often referred to as the "Cyprus Peace Operation".
Monday's judgment comes as the Turkish and Greek Cypriot communities are making a new effort to reunite the island.
Speaking ahead of the ruling, Turkish Foreign Minister Ahmet Davutoglu warned that a judgment against Turkey would come at a delicate time and said that he viewed it as “neither binding nor of any value".
“Not only is it legally problematic, its timing is wrong,” Davutoglu added.
The court said it would be up to the government of Cyprus to determine how to award the damages but Turkey has not always complied with the court's rulings.
In a 1998 ruling, the Strasbourg court ordered Turkey to pay Titina Loizidou compensation for depriving her of property in the seaside city of Kyrenia.
It was the first case in which a Greek Cypriot successfully sued Turkey over the invasion and earned the right to compensation.
Turkey paid the money in 2003 but has yet to comply with an earlier European Court decision ordering Ankara to allow the woman to reclaim her property.
Analysts noted that the case was notable not only because of its size, but also because it took Turkey to task for the invasion and awarded the money to Cyprus on behalf of individuals, a sensitive point that could affect current reunification talks.
“The big question is how the decision will affect the negotiations that are the most promising ever. It could put the talks into difficulty,” said Cengiz Aktar, an analyst on Turkey-EU affairs at the Istanbul Policy Centre.
Achilleas Demetriades, a prominent human rights lawyer in Cyprus, who has won several cases in the European Court involving Turkey, said that the judgment pertains to Turkey's failure to carry out an effective investigation of the whereabouts of Greek Cypriots who disappeared during and after the invasion of the island, and to provide that information to relatives of the missing.
Additional reporting by AP