Piratis,
No, no and thrice no.
Depending in large part of what and how a government interprets international law - that's why government's seek international legal counsel - will inform to some extent the policies that are taken. In the case of Turkey's intervention in Cyprus the government clearly thought that they had international law on their side insofar as it was justified on humanitarian grounds and T of Guarantee grounds. This the Turkish government has continued to maintain despite the fact that it is a set of arguments that have been rejected. If the Turkish government had the motivation (questionable) and capacity (undoubtedly) in 1974 (and onwards) to annexe northern Cyprus then they could have done so, but then the humanitarian or T of Guarantee justification would not have been available to it. Annexation is clearly and unequivocally illegal in international law.
Now why on earth would the Turkish government suffer the continuing condemnation re Cyprus intervention if its real underlying purpose was to annexe Cyprus ? Why didn't it just say 'sod this humanitarian mallarky we might as well just annexe for the trouble its worth, its what we wanted anyway' ? You might as well be hung for a sheep as a lamb.
The operation of international law and the campaign of the RoC government in international law rests precisely on the difference that I highlighted above. Turkey in Cyprus is an occupying power not an annexing power, and that's what the ECHR amongst others sees as the basic relationship. A world of difference.