President Clinton will travel to Aachen this morning to accept the International Charlemagne Prize for his contribution to European unity. This is the second day of a two-day German visit for the President, during which he will also take part in a conference of centre-left leaders in Berlin.
Mr Clinton's visit comes at a time when relations between the US and Germany - once seen as Washington's most important ally in Europe - are more turbulent than they have been for many years. Some disputes between the two countries are relatively trivial - such as a row over the size of the new US embassy in Berlin and Washington's refusal to support Germany's first choice as head of the International Monetary Fund.
But officials on both sides acknowledge that the fundamental problem is deeper and more intractable because it goes to the heart of the united Germany's role in the world. The Chancellor, Mr Gerhard Schroder, has complained that the US has been pressing the "new Germany" to take on more responsibilities. However, every time Berlin becomes more assertive, Washington tries to slam on the brakes.
Thus, Washington wants Germany to send thousands of soldiers to Kosovo, to increase defence spending and to stimulate its economy by privatising more state-owned companies and allowing employers to sack workers more easily. But the US has watched with unease as Germany and its EU partners have attempted to co-ordinate defence spending and establish a European military identity by forming a 60,000-strong rapid reaction force.
"The US says it wants a clear phone number for a Europe with some real cohesion. But when we try to give it one, we have problems," the German ambassador in Washington, Mr Jurgen Chrobog, stated yesterday.
For their part, Germany's politicians are unhappy about US plans for a national missile defence system and are unimpressed by Mr Clinton's offer to extend the system to some of Washington's allies.
Perhaps as a reminder of more harmonious days, the President has arranged a private meeting this evening with the former chancellor, Dr Helmut Kohl, who is facing a criminal investigation into his use of illegal political donations.
The conference which Mr Clinton is to attend tomorrow, "Governing in the 21st Century", will discuss globalisation and economic development's links to social security.
