Berlin — On May 23, Germany’s new foreign minister, Heiko Maas, will meet his American counterpart, Mike Pompeo, for the first time. The meeting will take place in rough times for trans-Atlantic relations, amid European worries over Donald Trump’s withdrawal from the Iran nuclear deal and a looming trade war. If Germany truly is the centerweight of Europe, then it matters enormously what its leading figure on foreign policy thinks. The thing is, no one knows.

Mr. Maas is no stranger to politics, but he is a novice when it comes to foreign policy. During Chancellor Angela Merkel’s last term, the 51-year-old Social Democrat served as the minister of justice and consumer protection, his first federal office. Before that, he spent nearly 20 years as a representative and government minister in the Saarland, a small state along the French border.

And yet, in just the 10 weeks since Mr. Maas took charge, he has already begun to leave his mark.

On March 26, only two weeks after he took office, Germany joined 28 other countries in expelling Russian diplomats in response to the poisoning of a Russian-British double agent, Sergei Skripal, and his daughter.

A few weeks later, Mr. Maas flew to Moscow for his inaugural visit with Sergei Lavrov, his Russian counterpart. Mr. Lavrov is one of the world’s most experienced diplomats, and someone known to bring the proverbial gun to every knife fight. One can only imagine the flurry of briefing papers and meetings at the German Foreign Ministry to get their new guy up to speed.