Owing to CONMEBOL's somewhat limited number of registered national football federations, countries from other continents are usually invited to participate to make up the 12 teams necessary for the current tournament format. Since 1993, two teams from other confederations, usually from CONCACAF whose members are geographically and culturally close, have also been invited. In all, nine nations have received invitations: Costa Rica (1997, 2001, 2004, 2011, 2016), Honduras (2001), Japan (1999, 2019), Jamaica (2015, 2016), Mexico (1993, 1995, 1997, 1999, 2001, 2004, 2007, 2011, 2015, 2016), Haiti (2016), Panama (2016), the United States (1993, 1995, 2007, 2016) and Qatar (2019). The United States was invited to every tournament between 1997 and 2007 but frequently turned down the invitation due to scheduling conflicts with Major League Soccer. However, on 30 October 2006, the US Soccer Federation accepted the invitation to participate in the 2007 tournament, ending a 12-year absence. At the 2001 Copa América, Canada was an invitee, but withdrew just before the start of the tournament due to security concerns. At the 2011 Copa América, Japan withdrew, citing difficulties with European clubs in releasing Japanese players following the Tōhoku earthquake and tsunami. Spain was invited to the 2011 edition, but according to the Royal Spanish Football Federation, they declined because they did not want to interrupt the Spanish players' holidays. At the 2015 Copa América, Japan declined the invitation as it would bring burdens to their overseas players, and China had to withdraw due to the Asian sector of qualification for the 2018 World Cup being held at the same time. At the 2021 Copa América invitees Australia and Qatar on 23 February 2021, announced their withdrawal from the tournament, due to the postponement of the remainder of the AFC Second Round of 2022 FIFA World Cup qualification to June 2021.