What is the fine-grained topic of the following text: On Monday, OPEC and its allies, led by Russia, scrapped a planned meeting in April and will decide instead whether to extend output cuts in June, once the market has assessed the impact of new U.S. sanctions on Iran due in May over its non-compliance with a deal to curb its nuclear program. Only return the topic.
OPEC and its allies' decision to postpone meeting and assess impact of U.S. sanctions on Iran