You must be joking about Gaddafi. Just because US did it does not mean EU could not have done it. In fact US(read Hiliary Clinton) has been criticized for creating a humanitarian crisis in Libya. US initialy supported the Libyan rebels and later bombed both Gaddafi and rebels. Now the country is unstable ready for radicals to take over.Many european country may be wealither then russia but when it comes to Russia combined europe wont be able to take them without USA helps
As is said earlier this European countries could not threw out Gaddif from libya without US help where gaddif libya army was nothing in comaprsion to UK/french/germany armed forces and here we are taking that they would take on russian army
And you think USA would allow such europe army to become strong .Well if such situation arises USA would fist have pop-corn and allow europe-russia fight and would jump in war at last moment to emrge hero
You are forgetting that NATO isnt just limited for defending Europe. NATO armies were in Iraq and Afghanistan. US has been using NATO against ISIS. Why should Euro countries do America's bidding if US threatens to pull back from NATO. Gaddafi may have posed some threat to EU, but then many NATO campaigns around the world have only benefited US.
US has much to lose if it pulls back, there is no popcorn. And EU nations are simply calling on Trump's bluff.