Israeli journalist and historian Gershom Gorenberg — whose history of the settlements “The Accidental Empire” is well worth reading — has recounted that in 1967, “the legal counsel of the Foreign Ministry, Theodor Meron, was asked whether international law allowed settlement in the newly conquered land.”

In a memo marked “Top Secret,” Mr. Meron wrote unequivocally, “My conclusion is that civilian settlement in the administered territories contravenes the explicit provisions of the Fourth Geneva Convention.”
In the detailed opinion that accompanied that note, Mr. Meron explained that the Convention — to which Israel was a signatory — forbade an occupying power from moving part of its population to occupied territory. [...]
Mr. Meron took note of Israel’s diplomatic argument that the West Bank was not “normal” occupied territory, because the land’s status was uncertain. The prewar border with Jordan had been a mere armistice line, and Jordan had annexed the West Bank unilaterally.
But he rejected that argument for two reasons. The first was diplomatic: the international community would not accept it and would regard settlement as showing “intent to annex the West Bank to Israel.” The second was legal, he wrote: “In truth, certain Israeli actions are inconsistent with the claim that the West Bank is not occupied territory.” For instance, he noted, a military decree issued on the third day of the war in June said that military courts must apply the Geneva Conventions in the West Bank.

Unfortunately, the Israeli government ignored Meron’s legal advice, and developed a series of shifting legal rationales to justify the annexation and colonisation of the occupied land, which has helped to create the exceedingly difficult and volatile situation we have today.