If they did do that then the EU could introduce a tariff on the fuel they import when they fly back in.

There would be rules around a fuel flight vs a legit passenger/cargo service, assuming they don't want to tax the extra fuel left in a plane at the end of a flight.

But that seem like a pretty straightforward problem to solve.

Making it even easier to implement: Commercial airline weights are carefully tracked for safety and efficiency purposes already, as are fuel levels. All the information needed to levy such a tax is already available.

It'll be more expensive to constantly fly back and forth to Dubai to load up than to simply pay the tax. Dubai is not that close to Paris. It takes about 7-8 hours. I don't know if you've been checking the news lately but Russia is out of the question for airplanes. They won't even return leased airplanes back anymore.

Switzerland, Norway and the UK are much closer though.

Switzerland and Norway at least would very likely accept such rules and implement them as well.

I'm Swiss and at least in Switzerland such a rule would automatically apply unless the population would do a referendum. And that would lead to a public vote that would almost certainty lose.

Most flights are local.

They aren’t going to russia for the Paris London flight.

No need, UK isn't in the EU.