Marc Perrin de Brimchambaut is a former French diplomat who served as Secretary General at the Organisation for Security and Cooperation in Europe from 2005 to 2011 and from 2015 to 2024 as a judge at the International Criminal Court in The Hague.
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The process that started early in the spring of 2025 reached a first stage at a conference in Paris on 4 September. It takes the form of a number of States putting together the elements that would contribute to a security guarantee for another State, to gain the support of a major actor and thus influence the course of ongoing negotiations, while the conflict is still active.
This approach differs from when States exchange pledges of assistance in case of threats to each other’s security. The exchange of pledges usually comes in a preventive or peace-building mode once a conflict is over. Article 7 of the North Atlantic Treaty and the Warsaw Pact were intended to solidify protection by two major powers to guarantee the security of allies in each group against an aggression, possibly by one of these two alliances. In the ill-fated Budapest memorandum (1994), the United States, the United Kingdom and the Russian Federation pledged to guarantee the security of Ukraine following its renunciation of nuclear weapons, in a peaceful context.
The declared purpose of the visits by Emmanuel Macron and Keith Starmer to the Oval Office at the beginning of Donald Trump’s second term may have seemed presumptuous. Both requested the US President to join them in putting together a reassurance force that would be deployed in Ukraine following a ceasefire or a peace agreement, to deter the recurrence of a Russian attack on Ukraine. The presence of such a force on the ground, at a distance from the ceasefire line, would provide a concrete security guarantee to Ukraine. A US participation in such a force was deemed indispensable for political reasons as well as for practical reasons, the United States being the indispensable provider of enablers in support of such a force. The US President’s reaction was less than enthusiastic: he had other plans and the Pentagon had no desire to join a still nebulous endeavour.
It took months of systematic consultations within a broad array of States for the two catalysts of this project, the Chiefs of Staff of the United Kingdom and France, to provide substance and credibility to the ideas of their leaders. In an open and collective process, they shaped what would be the composition of and plans for a reassurance presence that would serve as security guarantee for Ukraine.
A core component of French and British ground forces is envisaged, along with the potential addition of contingents from other countries (which have yet to pledge themselves openly) and the outside support of others, including Germany. More than 30 countries were active participants in the exchanges, including EU members, Norway, Turkey, Canada and Australia. NATO staff were involved at all stages, thus ensuring that the United States was well aware of what was going on. By late August the full plan was ready to be adopted by the political leadership of the group and formally presented to the US President.
In itself this process is a remarkable one. It is an initiative by Europeans to assemble a coalition of the willing around an ambitious and risky concept and obtain reluctant American support for it. It is shaped by an EU country and Britain, outside of the NATO or EU frameworks, as a coalition of the willing that reaches out to partners far afield. This may be a first exercise in the strategic autonomy of Europe, which has been a rhetorical objective so far, done in an ad hoc pragmatic way.
On 4 September the Heads of State and Government, communicating via a conference network, formally adopted the plan that had been prepared by their military and created a permanent structure, located in Paris, to serve as the framework for this initiative. They then communicated with President Trump, who had been fully briefed on the contents of the plan, in order to request an American contribution to key elements, should this plan be implemented. The details of the US response are not known, but it is understood they were positive, allowing the United States to contribute to the work of the coalition staff created on 4 September.
Before any deployment of such a reassurance force is envisaged, there would have to be an interruption of the hostilities, whatever form it may take. The very hostile Russian reaction to the message coming out of Paris is an indication that the plan goes directly against the expectations of Moscow, which has consistently called for a neutral Ukraine with limited military capabilities. It is, therefore, unlikely that the security guarantees that such a deployment would represent would be recognised by the Russian side; but this is precisely what makes it precious. President Putin cannot be allowed to dictate the terms of future Ukrainian security while calling on his North Korean allies for extra troops; and Ukraine should be free to choose its future security arrangements.
The next steps in seeking peace in Ukraine are likely to be as difficult and unpredictable as the ones that occurred in Anchorage, and subsequently in Washington, in the course of August. The coalition which has crystallised around a plan for security guarantees for Ukraine is, however, likely to persevere, and to continue to play a role in seeking to influence the US-Russia dialogue, providing concrete options for future Ukrainian security. It provides a framework for its members to consult on a continuous basis and plan for future options. In itself this is already a remarkable achievement, creating a new framework for cooperation among a strong group of like-minded countries that, together, have shaped what could be a key element of a future security regime in Ukraine. As long as this group benefits from strong leadership, it will continue to be a factor in a strained conflict that has been ongoing for three years.
