Say there is a non-NATO, non-EU country, yet not Ukraine, at least not yet. (I stipulate the last because I don't want the current crisis to yet color the answers.)

What are the actual requirements as listed in the treaties or charters for defense and/or aid to be provided by other member nations, if:

The country is granted EU, but not NATO membership?

The country is granted NATO, but not EU membership?

Do things drastically, or at all, change if both are granted?

  • 2
    Finland and Sweden are EU members but not NATO members, conversely Great Britain is NATO but not the EU Commented Feb 28, 2022 at 17:18
  • "Do things drastically, or at all, change if both are granted?" You get the benefits and the duties of both. The defense pact regulations simply add up. You'll have even more countries coming to your defense, at least on paper. Commented Mar 1, 2022 at 14:05

1 Answer 1


NATO has Article 5.

The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all and consequently they agree that, if such an armed attack occurs, each of them, in exercise of the right of individual or collective self-defence recognised by Article 51 of the Charter of the United Nations, will assist the Party or Parties so attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.

The EU has Article 42.7.

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.

Note the slightly stronger language ("all means in their power") for the EU, yet also the opt-out for the traditional neutrality of some EU member states. The EU explicitly acknowledges the NATO membership of many EU members, especially those with larger armed forces.

Commitments and cooperation in this area shall be consistent with commitments under the North Atlantic Treaty Organisation, which, for those States which are members of it, remains the foundation of their collective defence and the forum for its implementation.

Basically the EU does not require members to substitute European military structures for the existing NATO structures. But as far as assistant commitments go, they both appear clear. Neither has been seriously tested in war. The 9/11 attacks were a very special case.

The difference is which countries have to come to their aid. EU, NATO, or both.

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    Your conclusion is wrong. Based on what you posted, it is not clear that article 42.7 creates commitments. Specifically, "this shall not prejudice the specific character of the security and defence policy of certain Member States" allows for any member state to set its own defense policy which would preclude any specific commitment. Commented Feb 28, 2022 at 22:51
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    @DmitryRubanovich: Ultimately, all international law is customary. If you sign a treaty like that, and then many years later war breaks out, you can repudiate the term or you can "set a defense policy" that says you don't fight in wars (conveniently right after the war starts), but in the eyes of the international community, both of those actions are likely to be perceived in more or less the same way.
    – Kevin
    Commented Mar 2, 2022 at 6:00
  • They are different obligations. Article 42.7 says "aid and assistance", which could mean, for example, humanitarian aid and assistance. It is not clear that it refers to defense or assistance of a military nature. Whereas NATO's Article 5 specifically contemplates the use of armed force, in restoring and maintaining the "security", so it is more clearly calling for military defense.
    – user102008
    Commented Mar 10, 2022 at 1:29
  • @user102008, the EU says 'all means.' And the qualifier for Swedish neutrality shows that armed forces are the default assumption.
    – o.m.
    Commented Mar 10, 2022 at 5:10

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