The U.K.’s withdrawal from the European Union poses a number of challenges on both sides of the Channel, but Brussels should be alive to one particularly important risk: Brexit’s effect on Europe’s foreign policy.

The U.K. — in its capacity as a U.N. Security Council member, a nuclear power and a guarantor of approximately one-fourth of European defense capabilities — is one of the key pillars of the EU’s external action. Without Britain, the EU’s stance on the global stage may weaken, making it more vulnerable to external threats.

Fortunately, it’s not too late to avoid much of the damage.

The U.K.’s clearly stated commitment to Europe’s security, along with its weight and position within the European and Euro-Atlantic family, gives reason to believe that the EU and the U.K. can reinforce each other in defense and work together to defend joint European interests and values.

London is energetically engaged in global policy and will continue to play an important role in developing new and innovative approaches to international issues. Its economic, diplomatic and military capabilities could also mean the U.K. will take a front-runner role even after it leaves the bloc.

Close post-Brexit cooperation will be especially vital in the EU’s eastern and southern neighborhood, in the Western Balkans and in a common policy toward Russia.

The U.K. could even become a key partner for the EU in promoting common democratic goals in other countries. Indeed, Brussels should be ready to call on the U.K. to maintain close cooperation in order to minimize costs and maximize effects.

As a G7 member, the U.K. is an active promoter of our shared global agenda, known for coming up with creative and innovative solutions to common challenges. It is in our common interest to operate hand-in-hand going forward.

This is also in the U.K.’s interest. There are many situations in which concerted European action brings about a more positive outcome than steps taken by individual countries.

Close post-Brexit cooperation will be especially vital in the EU’s eastern and southern neighborhood, in the Western Balkans and in a common policy toward Russia. The EU and U.K. will also be stronger together when it comes to development cooperation, EU-NATO relations, counterterrorism and security, and defense policy, including sanctions.

It is in the EU’s interest to involve London in the area of security and defense policy as much as possible. Recently launched EU initiatives, such as the Permanent Structure Cooperation (PESCO), the European Defence Fund and the European Defence Industrial Development Programme, are still in their early stages. An inclusive approach toward the U.K. after Brexit would reinforce their effectiveness.

The EU’s Common Foreign and Security Policy (CFSP) is one of the least regulated areas of the EU integration, and therefore offers plenty of room to maneuver and shape a strategic partnership with the U.K.

Britain’s withdrawal from the EU is an unprecedented situation and as such requires unprecedented solutions. The future partnership therefore should allow continued British alignment with Europe’s CFSP in the form of political consultations and close cooperation. This should include coordinated action on the international stage, an exchange of information and fair burden-sharing, in full respect for the autonomy of the EU's decision-making process and U.K. sovereignty.

As former British Foreign Secretary William Hague rightly said, “nothing can beat being in the room.” After Brexit, the U.K. will not be physically present at EU meetings in Brussels, New York or other places. That is why we must ensure there is a constant flow of information between us, and that the U.K.’s voice is heard.

To be sure, there are still pending issues to resolve when it comes to Britain’s withdrawal agreement. As Brexit negotiations enter a decisive phase, we have a common responsibility to first ensure an orderly withdrawal and agree on the terms of our future relationship.

But foreign and security issues should be treated as unique — to ensure that they do not fall victim to possible disagreements on other issues. We also need to channel energy into forging an ambitious partnership in foreign and defense policy right from the date of the U.K.’s withdrawal.

The shape of the future EU-U.K. cooperation remains in our hands.

After all, our geopolitical situation will not change overnight, and the global security threats we face will not disappear after Brexit.

The EU will not find a partner closer than London. We share common values and a number of common interests. We are natural allies. We need one another to face rising challenges, to defend a rules-based world order and to secure a better future for next generations.

The shape of the future EU-U.K. cooperation remains in our hands. We strongly believe that if we combine efforts, we will manage to find constructive ways to make full use of a new, post-Brexit reality — for the common benefit of both the EU and the U.K.

Jacek Czaputowicz is the foreign minister of Poland. Linas Linkevičius is the foreign minister of Lithuania. Teodor Meleșcanu is the foreign minister of Romania.