1: Lausanne , Switzerland ( CNN ) Nuclear talks intensified Sunday between world powers and Iran , but key sticking points remained unresolved as the countries tried to reach a deal to curb Tehran 's nuclear program ahead of a Tuesday deadline . 2: The speed of which U.N . sanctions could be lifted remains in dispute . 3: Another sticking point : When would U.N. sanctions be lifted ?
1: sticking points 2: dispute 3: sticking point