In the wake of the Socialist victory in Spain, NATO officials are privately concerned about possible ''vulnerability'' on Europe's southern flank.
The Socialists pledged to hold a referendum on NATO membership, which has heightened worries over the possible disaffection of another member of the alliance, Greece. Since taking office a year ago, Greece's prime minister has insisted on a pullout when the time is right.
A combined pullout, officials say, could have a serious effect on the alliance - both militarily and politically.
But some NATO officials have been taking comfort in the apparent softened stand of Spain's Prime Minister-elect Felipe Gonzalez, who has been quoted as saying that although his party still opposes Spanish adherence to NATO, no date has been set for the referendum.
Political analysts here recall the anti-NATO remarks of Greek Prime Minister Andreas Papandreou during his campaign last year - but also his failure so far to take Greece out of NATO.