Merkel's mobile and US spying
Europe is insulted and offended by allegations that the Americans monitored Angela Merkel's personal mobile phone, but there are reasons why this will not become a deep rift between Europe and the United States.
Europe feels the need to register a protest and the summit in Brussels today provides such a platform. But there are plenty of voices advising that Europe must not be naive.
Thomas de Maiziere is Germany's defence minister and a close adviser to Angela Merkel.
He said Europe cannot return to "business as usual" in its relationship with Washington, yet he felt it necessary to say that the Americans "are" and "remain" our best friends.
But these revelations have done damage.'Punch in the face'
In Germany it is widely believed that, in saying that the US "is not monitoring and will not monitor" the chancellor's phone, President Obama deliberately left open the question that her phone might have been listened to in the past.
One German paper called the alleged snooping "a punch in the face of German security agencies". Another labelled it "the worst imaginable insult".
It offends, too, because Angela Merkel governs by her mobile phone.
She is often seen to be checking it or even sending texts at political rallies.
She is a leader who has spoken of President Obama as a friend and he has praised her for her leadership - and yet, for all that, it seems she may have been a target for US intelligence.
Germans, with their memories of Nazism and Communism, will resent these allegations.
The French, too, are not willing to let this pass.
Michel Barnier, the EU's internal market commissioner, says that "enough is enough".
He said on Thursday that not only had confidence in the US been shaken but he wanted to develop a "European data cloud", independent of American oversight.
French President Francois Hollande had spoken to President Obama on Monday after a French paper said the Americans had monitored millions of French calls.
Washington said some of the French reports were false, but even so the French president wants to put American spying on the summit agenda.
His poll ratings are low and he is under fierce criticism for his leadership even within his own party.
He may find a row with the US a useful diversion.Trade talks
But even in France there are voices counselling caution.
One former foreign minister said: "Let us be honest, we're eavesdropping too" - but then went on to say that it was the magnitude of the American operation that had shocked.
There is another reason why this argument will not be allowed to become a long-lasting rift, and that is trade.
The Americans and the Europeans have started discussing a free trade deal with potentially huge benefits to both sides.
In Brussels the deal is regarded as a strategic priority.
So, precise answers will be demanded of the Americans. The Europeans will want guarantees the practices have stopped.
It is an irony that a president who was feted by Europeans for not being George W Bush finds himself under fire.