MAHMUD HAMS/Getty Images
- European nations say they're planning a $4.3 billion joint air and missile defense system.
- Creating an Iron Dome similar to Israel's 'is necessary," Poland's PM Donald Tusk said.
- The European Sky Shield Initiative involves 21 countries and aims to enhance NATO's defenses.
European countries are preparing to reveal plans for a $4.3 billion Iron Dome-style air and missile defense system, Poland's prime minister announced on Monday.