Why NATO or any other organisation/country can handle the Mistrals without modifications.

How NATO or any other organisation/country would be able to handle the Mistrals if they decide to buy them as the ships have been modified to fit Russia's needs?:

Mistrals built for Russia include changes in hull construction to enable them to be used in northern latitudes, including in ice conditions. The height of the vessels has also been increased due to modifications to the ships' internal hangars to allow them to accommodate large helicopters like the Ka-52K and Ka-27PS.

Additionally the vessels have been modified for the installation of extra armament, including anti-air systems and large calibre automatic weapon stations for combating surface threats. The logic behind increasing the vessels' onboard armament is to enable the Russian Navy to use them in the open sea with a smaller escort.

Basically, there is nothing to change if NATO, the EU or any other country decides to buy them.

They can be used as other Mistrals except that they are able to go to northern latitudes and as they have been modified to accommodate bigger helicopters, they can accommodate the same helicopters as the previous Mistrals without any modification.

So, if you hear that NAT/EU could not use the Mistrals if they buy them because of the modifications brought for Russia's needs, you got the answer...

He who can do more can do less.

Source: janes.com"