French Defence Minister Jean-Yves Le Drian made a formal request for help from EU partners on Tuesday after the attacks in Paris on Friday, which had claimed the lives of 129 people and left hundreds injured.

This constitutes the first time that the so-called mutual assistance article of the Treaty on European Union has been invoked.

At a meeting of defence ministers of the EU member states in Brussels on Tuesday, Le Drian tweeted that he had just invoked Article 42.7, the Guardian reports.

Article 42.7 stipulates that: “If a Member State is the victim of armed aggression on its territory, the other Member States shall have towards it an obligation of aid and assistance by all the means in their power, in accordance with Article 51 of the United Nations Charter. This shall not prejudice the specific character of the security and defence policy of certain Member States.“

EU High Representative for Foreign Affairs and Security Policy Federica Mogherini said that all the remaining 27 member states had offered “full support and readiness to provide all the aid and assistance needed”.

France has not yet invoked Article 5 of the North Atlantic Treaty, which stipulates that an armed attack against one member state of NATO should be considered as an armed attack against them all.

This article gives all parties to the treaty the right to wage war as an act of self-defence under the UN Charter.

So far, Article 5 has been invoked only once – by the United States (US) after the 9/11 attacks.