One cannot see what happened to Niebel over the weekend in isolation. The Israelis are testy because they have noticed that, over the last few months, many good friends of their nation have begun to drift away. French President Nicolas Sarkozy, Italian Prime Minister Silvio Berlusconi and German Chancellor Angela Merkel all belong to that group.

German-Israeli relations are in a state of crisis. The arrogance of the administration of Israeli Prime Minister Benjamin Netanyahu is to blame. Via his security advisors, he let Merkel know that she was not to say anything publicly about the Israeli settlements policy during Netanyahu's visit to Berlin. He represented a critical telephone call as a positive chat. And he declined a prisoner exchange that had been put together by Germany's foreign intelligence agency, the BND, which could have brought captured Israeli soldier Gilad Shalit home from the Gaza Strip. Israeli Trade Minister Binyamin Ben-Eliezer, interviewed in the current issue of SPIEGEL, described the latter as a mistake.

The goals of the Gaza blockade include bringing Shalit home and isolating Hamas -- but not to punish the civilian populace of the coastal area. What has happened is exactly the opposite. Israel has not just denied a visit by a German minister. For months it has also been blocking the entry of building materials necessary for the construction of the German waste water treatment plant.

Either with a view toward populism or because he is genuinely upset, Niebel rubbed salt into the wound. He has not called off his visit altogether, as he said he would at first -- that would have been a real scandal. Instead he went to Israel. But he did not remain silent, as the Israeli administration expected him to. He came and he spoke out about his concerns.

It is a lesson that Israel must learn: Real friends can be critical of one another...