Part of the problem with voter registration was a lack of agreement between Polisario and Morocco over who could claim Saharawi ethnicity and who should be allowed to vote on the referendum. Morocco interpreted a December 1991 broadening of the voter eligibility criteria "as a license to submit applications on behalf of individuals with questionable ties to the Western Sahara." In addition, Morocco may have "improperly influenced Sahrawi tribal leaders who live in the Moroccan-controlled Western Sahara." The UN moved 373 peacekeepers into the area to help validate Western Saharan voters. Polisario believed that Morocco was identifying tribal groups as voters who did not have a close connection to Western Sahara. During this time, King Hassan also moved 37,000 people from Morocco into Western Sahara to act as potential voters, which "infuriated Polisario and shocked the peacekeepers." Polisario believed that limiting voters to those were listed as "Western Saharan" on the 1974 Spanish census would lead to a vote for independence and did not want additional voters identified.