German Chancellor Merkel attends a session of Bundestag in Berlin

What were they thinking?

In the wake of last fall’s revelation that the National Security Agency had wiretapped German Chancellor Angela Merkel’s cell phone, the report of U.S. intelligence’s involvement in two other likely cases of spying on Germany is mind-boggling.

Now the story has taken a dramatic new turn, with Germany expelling the CIA chief of station in Berlin — an almost unprecedented step by an ally. This unusual action reflects how seriously the Merkel government takes these spying allegations.

What could the CIA hope to gain by infiltrating the BND, the German Federal Intelligence Service, knowing there was a chance that the operation might be exposed? What was worth this risk?

U.S. President Obama and German Chancellor Merkel address joint news conference in the White House Rose Garden in WashingtonCIA and White House officials have said little to answer the question. But the fact that German industry has strong ties to both Russia and Iran may offer a clue. So economic and political intelligence about Germany’s contacts with those countries could be high on the list of potential U.S. intelligence targets. The CIA might for example, be interested in whether the Merkel government – heavily dependent on oil imports from Russia – is thinking about softening its opposition to President Vladimir Putin’s support for Russian-speaking separatists in eastern Ukraine.

Identifying possible terrorists under surveillance by German intelligence agencies could be another reason. Both the CIA and the FBI are keenly aware that the 9/11 al Qaeda plot that brought down the twin towers of the World Trade Center was hatched in Hamburg. Germany has long served as a transit hub between East and West, and it also has a sizable Arab immigrant community.