Meanwhile, PSOE's stance on NATO came closely linked with the negotiations for Spain's entry into the EEC. The PSOE had campaigned in 1982 for the holding of a referendum on the issue after Leopoldo Calvo-Sotelo's unpopular move to enter NATO in May 1982, and it had also opposed the country's permanence within the Atlantic Alliance. However, once in power Felipe González' stance evolved to one of "support" to NATO. According to Santos Juliá, the main factors that influenced the PSOE government's change of attitude were "pressure from the United States and several European countries; the connection between staying in NATO and Spain–EEC negotiations and the growing favorable stance of the Spanish Defence Ministry to attain closer ties with the Alliance". By 1985, as Spain had signed the Act of Accession to the EEC, preparations for the referendum on NATO membership started, being eventually held on 12 March 1986. Previously, González had to convince of the new government's stance to his own party in the 30th party congress held in December 1984, and the turnaround on the NATO issue led to the resignation of his Foreign Minister, Fernando Morán, in disagreement with him.