Ukraine and the significance of the European Union's mutual-defence obligation

The Deutsche Welle News program To the Point presents this half-hour discussion of the Ukraine situation, Russia’s troop build-up: Will the West stand by Ukraine against Putin? 12/09/2021.

One of the panelists, Thomas Wiegold, journalist and author of the Augen Geradeaus! blog, observes just after 6:35 "we shouldn't forget that the EU as such also has a mutual defense clause which in itself is even stronger than the NATO defense clause."

Neither the EU nor the NATO treaties require mandatory sending of troops by all members in the case of a defence action under the treaties. But both are serious commitments.

And those mutual defence obligations are major considerations in incorporating Ukraine, Georgia, or Moldova into the EU or NATO while Russia is in de facto control of parts of their national territory. That's especially so in the case of Ukraine, where Russia has formally (though in violation of international law) incorporated the Ukrainian territory of Crimea into Russia itself.