BERLIN – The celebrations of the 20th anniversary of the fall of the Berlin Wall started off well enough – former President George H.W. Bush, ex-Soviet General Secretary Mikhail Gorbachev, and former West German Chancellor Helmut Kohl gathered in front of nearly 2,000 dignitaries in Berlin last week to celebrate their role in bringing about the end of the Cold War.

It was a happy affair, with Mr. Bush and Mr. Gorbachev exchanging laughs and smiles as they recalled Nov. 9, 1989, a day that all agreed advanced world freedom and ended the looming threat of the cold war.

But in the week since, as leaders have gathered here to mark the Mauerfall anniversary, agreement has been tough to come by and fractures between allies have shown themselves in what has been billed as an event to celebrate unity. One of these signs was the absence of US President Barack Obama as other heads of state gathered underneath the Brandenburg Gate Monday night to make a symbolic journey from the old East Berlin to West Berlin. They group then toppled a wall of dominoes along the path of the Berlin Wall.

But President Obama sent Secretary of State Hillary Clinton is his place, infuriating many Germans, as the US president is beloved here. Some in Berlin asked if this snub indicated that the alliance between the US and Germans is strained.

The events of the last week have fueled German concerns. As German Chancellor Angela Merkel was flying back from Washington after meeting with Obama and giving a speech to US Congress, General Motors, whose board was appointed by the Obama administration, canceled a deal that would have saved German automotive jobs. Ms. Merkel was stunned and angry. The White House didn’t comment.

Then Ms. Clinton, speaking last night at a dinner here, took what many perceive as a shot at Germany for failing to commit additional troops to the war effort in Afghanistan. The wall celebrations should be “should be a call to action, not just a commemoration of past actions,” she said. “'That call should spur us to continue our cooperation and look for new ways that we can meet the challenges that freedom faces now … We owe it to ourselves and to those who yearn for the same freedoms that are enjoyed and even taken for granted in Berlin today.”

French President Nicolas Sarkozy has also found himself in bit of a political pickle following some claims he made about being in Berlin on Nov. 9, 1989. Soon after Mr. Sarkozy posted a picture that shows him picking at the wall with a hammer on what he claims is Nov. 9, journalists and former French officials immediately began questioning his story. This is hardly a scandal, but it drew attention away from a major diplomatic event. It also comes as Sarkozy is trying to build closer ties with Germany, despite Merkel’s resistance.

Meanwhile Russian President Dmitry Medvedev, representing the direct descendant of the defeated Soviet Union, has said and done all the right things. He praised the collapse of the wall and offered praise for Germany’s advances in the past two decades.

Of course, Mr. Medvedev has reason be happy with Germany’s progress; Berlin and Moscow rely on one another as key economic partners. Who would have thought it 20 years ago?