I really do not think that you understand the enormity of the treachery of Russia in its dealings with Ukraine, and, to a lessor extent, the treachery of the US with the EU looking on limp wristedly.
In 1994 Ukraine had the world's third largest nuclear arsenals. However, the US and Russia persuaded Ukraine to give us its arsenal in return for guaranteeing its borders (the Budapest Memorandum).
By annexing Crimea Russia has shown its willingness to tear up treaties willy nilly. Shame on the US and EU for allowing this to happen. The EU has five distinct land borders with Ukraine, it should have had the power to stand up to this bullying of its neighbour. It didn't.
This is not the first time that Western Europe has stood idly by while Russia has bullied Ukraine. The 1932-1933 holdomor killed an estimated 2.5-7.5 million Ukrainians, possibly a greater slaughter than the Holocaust if non-Jewish victims are excluded. Stalin went unpunished.
I do not agree with all that Boris Johnson says, but he is right when he calls Russia a pariah state. It should be treated as such and isolated.
I really do not know enough about the ideas of an EU army to know what form it would take: a loose allegiance of states acting under a unified command like the UN does in its peacekeeping roles; or a closer alliance like NATO; or even a fully integrated force acting more like a national army. But what I do know is that it would be no bad thing if the EU had the ability to project military power as a unified force to stand up to present and future threats (though perhaps not with Junker as its commander-in-chief).