NATO governments will decide within a few weeks how many countries they will invite to join at the Prague summit in late November, Secretary-General Mr George Robertson said.
"I don't expect that the 19 [NATO member] governments will make their decision until they are absolutely clear in their own minds that all of these countries will add value to NATO's military capabilities as well as to NATO's outreach and the wider stability," he said.
There are nine applicants for NATO membership - Albania, Bulgaria, Estonia, Latvia, Lithuania, Macedonia, Romania, Slovenia and Slovakia. The alliance is expected to invite in all but Albania and Macedonia.
Many of the countries applying for membership of NATO are also hoping to join the EU following Ireland's ratification of the second Nice referendum.
Mr Robertson had talks yesterday with with US President Mr George W. Bush and Defence Secretary Mr Donald Rumsfeld.
Mr Bush said the United States would soon spell out its position on expanding the alliance. "I told him [Robertson]that we would give him a definite answer about our views on expansion in a couple of weeks, and that timetable seemed satisfactory with him," Mr Bush said.