The refusal of Prime Minister Benjamin Netanyahu of Israel to receive the German foreign minister because of a meeting the German held with a veterans’ peace group is not in itself a major incident in Israeli-German relations. Germany’s history alone ensures it will remain Israel’s staunch supporter. What is troubling, rather, is Mr. Netanyahu’s increasingly illiberal pattern of treating critics of Israel’s occupation of Palestinian lands — domestic and foreign — as enemies.

The flash point in this case was a meeting Germany’s foreign minister, Sigmar Gabriel, held with some nongovernmental groups while on a visit to Israel. One of these groups, called Breaking the Silence, is particularly reviled among right-wing Israelis because it gathers anonymous testimonies from Israeli soldiers about their service in occupied territories, often highlighting hardships imposed on the Palestinians. So Mr. Netanyahu canceled his meeting with Mr. Gabriel, proclaiming that he would not welcome diplomats who met with organizations that, he said, “slander” Israeli soldiers.

It is understandable that Breaking the Silence would rankle some Israelis, because it raises questions about one of the most respected institutions in Israel — the army. And there can be a debate about whether Mr. Gabriel was unnecessarily provocative. But Breaking the Silence has support from former high-ranking Israeli military officers and has generated debate about what kind of society Israel wants to be. More broadly, the occupation, now approaching 50 years, has been consistently criticized by the United States and much of the rest of the world, and has been a source of fiery debate within Israel.