EN
AT A GLANCE
EPRS | European Parliamentary Research Service
Author: Sebastian Clapp with Anne Verhelst, Members' Research Service
PE 739.250 – December 2022
A comparative analysis of Article 5 Washington
Treaty (NATO) and Article 42(7) TEU (EU)
The Russian aggression against Ukraine has highlighted the relative confusion that exists over the obligations
that states have under Article 5 of the (NATO) Washington Treaty and Article 42(7) of the Treaty on European
Union. Clarification and explanation of these articles has become particularly urgent as overlap between NATO
and EU membership increases, following Finland and Sweden's application to join NATO.
Background
Article 5 of the 1949 North Atlantic Treaty is considered
the cornerstone of the NATO Alliance, embodying its
'one for all, and all for one' spirit. When one of the 30
(soon to be 32) NATO members falls victim to an armed
attack, all other members must come to that state's
assistance. This assistance may include the use of armed
force. When the treaty was negotiated, in 1948 and
1949, the western European nations favoured an article
implying an automatic and unqualified commitment of
the US to defend Europe. The US, however, feared that
such a strong wording would automatically engage
them in European wars, something Congress did not
want to accept. The negotiations ended in a
compromise: the security guarantee was laid down in a
formal treaty (a European demand), but embedded in an
Article 5 formulation that does not imply automatic US
involvement in an armed conflict (an American
demand), and is strengthened by Article 11. Sixty years
later, Article 42(7) was incorporated in the Treaty on
European Union (TEU) as the EU's 'mutual defence
clause', part of a cluster of articles relating to the 'progressive framing of a common Union defence policy'.
Substantial uncertainty remains over the interpretation of Article 42(7). Following its first and only
invocation in 2015, after the November terrorist attacks in Paris, debate intensified on how it works in
practice, its scope, the definitions of 'armed aggression' and 'territory', and which forms of aggression it
applies to (e.g. whether those include hybrid threats). Experts note that Article 42(7) 'leaves more room for
interpretation than one might expect from a clause in a legally binding text'. Many experts hoped that the
Strategic Compass would deliver clarification, however that did not occur.
Comparisons of the two articles point to a number of differences. First, according to some views, the EU's
mutual assistance pledge can be seen as more strongly formulated, in that EU Member States have an
explicit obligation to come to the defence of the victim state, and that they have to do so by 'all means' in
their power, not just the means they think are necessary. Article 42(7) is thus, according to that analysis, of
a much 'more compelling nature'. Second, according to legal experts, the threshold to invoke – armed
aggression (Article 42(7)) as opposed to an armed attack (Article 5) – is lower in international law. Not every
act of armed aggression reaches the threshold of an armed attack triggering the right to self-defence under
Article 51 of the UN Charter. For instance, according to an expert view, a naval blockade of a harbour would
constitute armed aggression but not necessarily an armed attack. However, others suggest the reference
to 'armed aggression' may just be the result of a 'literal translation of the French text', rather than signifying
a broader scope. Third, in terms of scope, while Article 5 applies to all NATO members in the same manner,
Article 42(7) TEU states that 'this shall not prejudice the specific character of the security and defence policy
Article 42(7) Treaty on European Union
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.
Commitments and cooperation in this area shall be
consistent with commitments under the North Atlantic
Treaty Organisation...
Article 5 Washington Treaty (NATO)
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
suchanarmedattackoccurs, eachofthem,inexerciseofthe
right of individual or collective self-defence recognised by
Article 51 of the Charter of the United Nations, will assist the
Party or Partiesso attacked bytaking forthwith, individually
and inconcertwiththeotherParties, suchactionasitdeems
necessary, including the use of armed force....
EPRS Article 5 Washington Treaty (NATO) and Article 42(7) TEU (EU)
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of certain Member States'. This is commonly understood to give 'special status' Member States (e.g. neutral
states Malta, Ireland and Austria) an opt-out from mutual defence assistance. Article 5 has no such opt-out.
Geographical scope
For Article 5 to be applicable, an armed attack has to occur on the territoryof aNATO member. The territorial
limitation of Article 5 is found in Article 6, which delimits the area in which the armed attack has to take
place (North America, Europe and other clearly defined areas north of the Tropic of Cancer). However, it sets
no geographical limit on where Article 5 counter-actions may take place. If, for example, Article 5 is
triggered by an armed attack on a NATO member's soil, academics maintain that there is no inherent legal
impediment to NATO carrying out collective self-defence measures in a third country, even as far away as
Singapore. Article 42(7) does not entail any such strict geographical limitation. By referring to 'its [Member
State's] territory', it would seem to refer not only to continental Europe but could have worldwide
applicability. Questions also remain about the applicability of Article 42(7) to the hybrid, cyber and space
domains, while NATO leaders established at the 2022 Madrid Summit that Article 5 is applicable in those
domains. The November 2022 EU cyber-defence policy does note that, in cases of significant cybersecurity
incidents, Member States 'need to be able to draw on mutual assistance... in the context of Article 42(7)'.
Legal obligations for members
If the North Atlantic Council (NAC), NATO's highest decision-making body, reaches a consensus
determining that an armed attack has occurred within the North Atlantic area, NATO Member States are
obliged to assist the victim member. However, academics posit that this obligation is caveated by the fact
that it falls to each country to decide how exactly it will respond. Still, this discretionary element does not
remove the fact that NATO members must determine the necessary action in good faith, so their response
cannot be manifestly unreasonable (e.g. sharing redundant information after Russia carries out an armed
attack on a NATO member). In terms of Article 42(7), when first invoked after the 2015 attacks in Paris,
Member States clarified that 'no formal decision or conclusion by the Council will be required to implement
Article 42(7)'. The French Minister of Defence referred to the invocation of Article 42(7) as a 'political act' and
the then EU High Representative underlined that no 'further formality' was needed to launch mutual
assistance. Therefore, in practice, no formal requirement to adopt a decision to trigger Article 42(7) has
been established. In terms of what 'aid and assistance by all the means in their power' means, a lot remains
uncertain. Some experts note this has been deliberately left 'ambiguous' to accommodate neutral and nonaligned
Member States. When France invoked the article, requests and offers of assistance were discussed
and organised bilaterally rather than through the EU, and took various forms.
Past invocations
Article 5 has been invoked only once, in the wake of 9/11. The NAC invoked it symbolically on
12 September 2001, but added that the attack needed to have 'come from abroad' to fall under Article 5.
On 2 October 2001, after the NAC had been briefed by US officials about the investigation, the NAC
determined that the attacks were directed from abroad, i.e. from Afghanistan. Consequently, the NAC
confirmed the invocation of Article 5 and agreed on eight measures, including sending NATO aircraft to
patrol US skies. This suggests that Article 5 cannot be invoked in response to domestic terrorism. By
contrast, Article 42(7) was invoked, also only once, precisely in response to terrorism stemming from within
the bloc. France invoked Article 42(7) in the aftermath of the 2015 attacks on the Bataclan. EU Member
States unanimously expressed political support to and solidarity with France, and within days several came
to the assistance of France in different ways, ranging from military assistance (e.g. contributions to airstrikes
in anti-ISIS operations in Syria and Iraq) to non-military assistance such as increased intelligence-sharing.
European Parliament position
The draft annual report on common security and defence policy (CSDP), currently under discussion in
Parliament's Committee on Foreign Affairs, stresses the need to make Article 42(7) TEU operational in the
short run and to clarify the coherence between the EU's Article 42(7) and NATO's Article 5. In its 2021 annual
report on CSDP, Parliament urged Member States to reach an 'ambitious common understanding' on
Article 42(7), including in a hypothetical cyber-attack scenario. It also underlined that the conditions for
activation of the article and the modalities of the assistance required have not been clearly defined.