In an article in the Frankfurter Allgemeine Zeitung, Mr Ruhe suggested Germany should play an increased role in the successor force, which might have a German chief of staff. But Nato sources ruled out any suggestion that the force would have a German commander, which would be unacceptable to the US and the Serb population of Bosnia.
Nato member states are keeping quiet about the question of a successor force and the US has refused to comment until after the presidential elections on 5 November. However, the British Army is planning to keep a strong force in Bosnia until April.
The present head of I-For is the US Admiral Joe Lopez, commander of Nato's southern region in Europe (Afsouth). His force comprises three multinational divisions - one US-led, one UK and one French.
Nato wants to base the successor force on Landcent - the land component of Nato's central European region (Afcent). Afcent's commander is a German, General Dieter Stockman. US troops, who would be needed to make any successor force credible, would not be placed under German command.
However, the US commander of Landcent, General William Crouch, is a prime candidate.
Mr Ruhe said that if Landcent forms the nucleus of the post I-For command, a German might be appointed to to a senior position - possibly the chief of staff.
I-For's three divisional headquarters, with up to 20,000 troops each, will be replaced by brigades of about 7,000 troops.