Euractiv has posted a summary of problems facing NATO over the enlargement of the Alliance. It includes some good quotes from a variety of sources. They make the point that this has divided the EU as well as NATO, largely along the lines described by Donald Rumsfeld when he referred to 'old' and 'new ' Europe.
The difficulties over Ukraine and Georgia, in particular, highlight the need for the US to do more than simply declare its intent before NATO takes big decisions. There has always been a need for careful diplomacy to move along an Alliance that acts by consensus. In this case, the necessary groundwork has not been done, and as Jan Marinus Wiersma is quoted by Euractiv as saying, the US has been too hasty in promising MAPs to the Ukraine and Georgia.