BRUSSELS — This week leaders from the G-7 countries will meet in Canada to discuss some of the key problems facing the world today. The agenda of the conference is guided by themes like gender equality, preparing for jobs of the future and foreign threats to our democracies.

But there is no hiding that our talks will be held in the specific political context of President Trump’s recent decisions and the reactions they have provoked on both sides of the Atlantic. By which I mean the United States’ withdrawal from the Paris climate agreement and the Iran nuclear deal, and the new tariffs on steel and aluminum, including the way they were imposed and the arguments used to justify them. To me, an incurable pro-American European fanatically devoted to the idea of trans-Atlantic cooperation, these decisions are unfortunate and worrying.

The crucial question today is whether these decisions are only incidental changes to current American policy (to which, of course, every president is entitled) or the beginning of a new strategic trend. Simply put: Are they merely seasonal turbulences or rather the first symptoms of the breakup of the Western political community, which the G-7 represents and informally leads? It’s inevitable that this will be on everyone’s mind at the conference, given the signals that Washington may not be interested in reconfirming our shared commitment to the rules-based international order as one of the main aims of our group. This is no laughing matter. The alternative to order is disorder.

When I hosted Vice President Mike Pence and, subsequently, President Trump in Brussels last year, I expressed my belief that it is in the West’s interest to maintain a rules-based international order in which brute force and egoism do not determine everything. That rules-based order can be enforced only by a common, mutually supportive and decisive policy of the whole Western community. For millions of people worldwide, the West’s predictability and stability guarantee or, at the very least, offer hope that chaos, violence and arrogance will not triumph. Whoever wants to demolish this order must know that we will stay united in its defense. I will make this case to the other participants of the G-7 conference. After all, our community cannot be blown apart by aluminum tariffs.