Europeans have increasing doubts that President Trump remains committed to the NATO alliance and the mutual defense it ensures. And so they are talking more seriously about their own little-known guarantee for collective defense, an article buried in the European Union’s governing documents.
Long dismissed by many as unworkable and even unnecessary given the well-established NATO alliance, Article 42.7 of the E.U.’s Treaty of Lisbon obliges member states to provide military, humanitarian and financial aid to other members in case of attack. Meant to complement NATO, it has been used only once, when France invoked it after the November 2015 terrorist attacks in and around Paris.
But with Mr. Trump intermittently threatening to leave NATO over member countries’ refusal to support the war in Iran, this moment is profoundly reshaping both the alliance and the European Union, said Camille Grand, a former NATO official who is the secretary general of ASD Europe, a trade association for defense industries.
He said the Trump administration’s evolving position “creates the need to defend Europe with less America.”
As E.U. leaders gathered for an informal meeting in Cyprus this week, their agenda included a discussion of the Lisbon Treaty provision. They plan to conduct an exercise next month, when senior diplomats who deal with security matters will think through how it might work in practice.
Radoslaw Sikorski, Poland’s foreign minister and former defense minister, is skeptical that it would work very well.
“You cannot do serious European defense without treaty change, and right now that is unachievable,” he said. He points out that the European Union cannot finance military operations out of its budget, and that member states are reluctant to commit their own troops and money to an operation they cannot directly control.
Each nation has its own legal requirements, caveats and strictures for rules of engagement, he said, and there are language problems and built-in confusion over who exactly would command any pan-European operation.
“I despair as to what has to happen for us to get serious” about defense, Mr. Sikorski said.
NATO’s famed Article 5, which commits member states to collective defense, in fact only requires them to consult about how to respond to an attack. It has also only been used once, when it was invoked to help defend the United States after 9/11.
On paper, the E.U. provision appears stronger, because it requires commitment to aid a member state under attack.
But NATO is a single-issue organization, just about defense, with a streamlined decision-making process, a clear hierarchical structure and one dominant power — the United States — that calls the shots. The European Union, by contrast, is a far more complex and inefficient “compromise machine,” said Jan Techau, a former German defense official who analyzes European security for the Eurasia Group, a consultancy.
When people talk about European security, some see the E.U. provision as “the way to go,” Mr. Techau said. “But I don’t think there’s much of a future in it, because no one really wants to administer European security through E.U. structures, which are too complicated.”
The tabletop test of 42.7 is intended to game out how it might function politically in an emergency, with a working paper to follow.
Before Mr. Trump, no one took the E.U. provision seriously, said Bruno Maçães, a former secretary of state for Europe from Portugal. But since NATO’s Article 5 “is less relevant,” he said, “42.7 is more relevant.”
Europeans are also trying to build on the idea of a “coalition of the willing,” which has discussed deploying European troops to Ukraine to monitor any peace settlement. Led by Britain and France, the same model has been used to discuss a European contribution to keeping the Strait of Hormuz open once hostilities end.
With Britain no longer a member of the European Union, some analysts see this nascent coalition as the foundation for a stronger European pillar within NATO that is also able to act outside it.
For non-NATO states like Ireland, Austria and Malta, the E.U. provision has added importance. But some E.U. states, especially from Central Europe and the Baltics, worry that too loud a discussion of E.U. collective defense would give Mr. Trump the excuse to further reduce his commitment to NATO.
Recent events have increased the urgency of the E.U.’s defense clause. First was Mr. Trump’s threat to seize Greenland, and then an Iranian drone strike on a British base in Cyprus, a member of the European Union, early in the Iran war. Italy, Germany and other member states sent help, even though the defense provision had not been officially invoked.
That’s why European officials have decided that it would be useful to clearly lay out how the measure works.
Yet the European Union’s push into defense has caused tension with member states and existing institutions, like NATO, and Mr. Grand, the former NATO official, sees the potential for more discord.
“Realignment can generate frictions,” he noted, while adding that if the players work together, European deterrence will be more effective and credible.
