"Our readiness for defence is not sufficient. It demands an urgent ramp-up and a longer term strategy how to replace American capabilities in Europe," commissioner Andrius Kubilius said.

"The forthcoming American withdrawal from Europe is a new reality."

Kubilius said Europe needs to avoid an "angry divorce" with Washington as US President Donald Trump's administration weighs shifting forces from the continent.

NATO countries look set to agree at a summit in the Hague later in the month to massively ramp up defence spending in a bid to keep Trump on side.

The EU for its part has launched a raft of initiatives worth some 800 billion euros aimed at helping countries bolster their defences.

Next week, Brussels is set to unveil proposals designed to slash red tape to allow Europe's defence industry to bolster production.

"Without this simplification, nothing else in defence readiness will be possible to achieve," Kubilius said.

"Red alert against red tape -- bureaucracy must not be an obstacle to our defence."

The call from the top EU official overseeing the defence industry comes after NATO chief Mark Rutte on Monday reiterated a warning that Russia could be ready to attack the alliance in five years.

Rutte called for a "quantum leap" on defence preparations and said that NATO needed to boost its air defences by 400 percent to face the threat.