Lower tariffs resulting in higher economic growth are reason enough for nations to sign free-trade agreements. But diplomatic dividends are also worth considering.

The proposed Transatlantic Trade and Investment Partnership (T-TIP) between the United States and the European Union, for instance, would tighten ties at a time when the West is increasingly challenged by geopolitical events. That’s the consensus of many security and diplomatic experts, including Johan Verbeke, Belgium’s ambassador to the United States. Verbeke, on a recent visit coordinated by the Minnesota International Center, told members of the Star Tribune Editorial Board that T-TIP would add “a very strong economic pillar” to what is “essentially a political-defense relationship.”

What’s more, the aggregate transatlantic economic clout would be so sizable that the pact would set standards. “We share the same values,” Verbeke said, listing open and competitive markets, playing by the same rules, and “the classical Western doctrine of what economics are about and how to be a fair and just society.”

Because international institutions designed to foster global order — including the European Union — are increasingly buffeted by crises of legitimacy, it’s in America’s best interest to provide support. In return, the U.S. gains economic and even military security. It’s disappointing that both the Republican and Democratic presidential front-runners have come out against the Trans-Pacific Partnership, a 12-nation trade pact that would boost world economic growth, provide a counter­balance to a rising China and offer allies a tangible result of the Obama administration’s diplomatic “pivot” to Asia.

Failure to enact the TPP might mean T-TIP does not advance, either, which would embolden those in Europe trying to weaken — or leave — the European Union.

Verbeke acknowledged that neither the European Union nor the free-trade agreements are without flaws. But, he added, “in politics generally, you have to live with the suboptimal. It’s only the idealists and very often the extremists who hold out for the optimal.”