Step 1: Understanding the Concept:
The European Union (EU) is a political and economic union of member states located primarily in Europe. The possession of nuclear weapons is determined by individual member states' national defense policies, not by the EU as a collective body.
Step 2: Detailed Explanation:
Within the European Union, only one member state officially possesses its own nuclear weapons: France.
The United Kingdom also possesses nuclear weapons, but it officially left the European Union in 2020 (an event known as Brexit).
Before Brexit, there were two EU countries with nuclear weapons. After Brexit, only France remains.
Some other EU countries (like Belgium, Germany, Italy, and the Netherlands) host U.S. nuclear weapons on their territory as part of NATO's nuclear sharing policy, but they do not own or control these weapons. The question asks how many EU countries *have* nuclear weapons, which implies ownership and control.
Step 3: Final Answer:
After the departure of the United Kingdom, France is the only country in the European Union with its own nuclear arsenal. Therefore, the correct answer is 1.