lol, FWIW, my own best guess at yet another 'interpretation'…
"Once the situation in the East is successfully resolved - and we all hope that this will be accomplished during the course of this summer -, then Europe will be able to, as the Führer would put it, 'for at least a while, be free to shift its focus entirely onto its internal matters' "
That the expression 'sich einstacheln' isn't easily found in dictionaries doesn't surprise me at all, because there are plenty of really old colloquialisms in the German language that have very unfortunately disappeared into the past, right along with the old folks who may have routinely used them.
I love these old expressions and have a relative in Europe still familiar with plenty of them .. will hopefully be able to clarify this soon :)
Stachel = thorn
Stacheldraht = barbed wire
The spiny 'Igel' (hedgehog) curls up into a ball when threatened
These literal translations all make sense, but I agree that in this case, the CONCEPT is what really counts ...