QUARKONIUM PRODUCTION AND COLOR DECONFINEMENT IN NUCLEAR COLLISIONS

The suppression of quarkonium production in nucleus-nucleus collisions was originally proposed as a signal of colour deconfinement. Strong ' 'anomalous'' J/psi, suppression in Pb-Pb collisions has been reported at this Conference by the NA50 Collaboration. Is this suppression real ly anomalous? Can we conclude that the quark-gluon plasma is already d iscovered? What has to be done next? I address these questions basing on the current theoretical understanding of quarkonium production and new precise experimental information.