There should be no nostalgia for the Cold War. Communism's collapse freed millions. But the state-centric, East-West divide seems to be yielding to an unwieldy era of chronic conflict, failed states and a revanchist Russia.

Western unity, increasingly rooted in the U.S.-German alliance, will enhance the chance of managing the chaos. Fortunately, Germany is rising to the challenge. U.S. policymakers should bear that in mind as they mull multiple international issues before Congress.

Germany's emergence was underscored by Peter Wittig, Germany's ambassador to the United States, in a visit to Minnesota last week. "In the perspective of the administration and many on the Hill, I think that Germany is the leading European power," Wittig told a Star Tribune editorial writer. But Germans are reticent, he said. "In a way, we've been propelled in kind of a leadership role in Europe that we didn't really actively aspire to, nor are we used to. So they are very hesitant. … Leadership comes not only with responsibility, but also with downsides," Wittig added, in an analysis of geopolitical leadership that might resonate in America. "Expectations are high, you have to satisfy a lot of stakeholders, the applause is rare, curtain calls never happen and the criticism is harsh."

Americans may indeed be weary, and Germans wary, of global leadership, but a vacuum would be worse. So it's encouraging that Germany has led a resolute response on several issues, including Ukraine.

"Our policy is we are not an equidistant mediator between Russia and Ukraine — we are siding with Ukraine in its aspiration to restore the sovereignty over its territory," Wittig said.

Germany's positions will be consequential in other continental crises, too, including the fiscal brinkmanship with Greece. Geography makes Germany less central than Mediterranean nations to the migration crisis, but Berlin realizes it must help lead a coordinated E.U. response. Wittig said that along with political and economic factors causing the crisis, there's "a resurgence of pre-modern factors" of ethnicity, religion and tribalism.

International institutions are mostly failing to contend with the chaos. The U.N. response has been better regarding Iran's potential nuclear weapons. The five permanent members of the Security Council and Germany have a tentative pact with Tehran. The final deal will be imperfect, but that won't be the enemy of the good in Berlin, where "we don't face the domestic skepticism that the administration is facing here," Wittig said. Accordingly, Congress should carefully consider that domestic U.S. politics risks the global unity that led Iran to negotiate in the first place.

Similarly, a proposed U.S.-E.U. free-trade agreement is a "highly important strategic project," Wittig said. "Are we willing to set the gold standards? Or are we somehow doubtful, and fail to seize that once-in-a-generation opportunity?" The same could be asked about the response to several spiraling crises worldwide.