Can the European Union defend itself?

Many European leaders have long pushed for a bigger military role. One that is independent of the US-led NATO alliance. The need for this increased military capability was recently made clear, during the chaotic evacuations from Kabul airport. European nations had to rely almost entirely on the United States. European Commission president Ursula Von Der Leyen says the bloc needs the political will to stand on its own. She says the EU should be able to deploy a military force without relying on the US or NATO. But what is holding it back from achieving this goal?