Saudi Arabia, one of the Middle East's most key and canny players, knows that by keeping oil prices low they can appease President Donald Trump, lowering gas prices and handing the president an easy political win. This has not gone unrewarded, and the Trump administration has signaled favoritism to Saudi Arabia. This is a political, rather than economic, decision.
Anyone who thinks that Trump, or any one figure, could have this impact on OPEC is unfamiliar with the inner workings of the world's oil cartel. Saudi Arabia is dropping prices as part of a tit-for-tat with OPEC's smaller partners who take advantage of supply gluts. By lowering prices further, OPEC+ is putting the squeeze on their partners who do not have the resilience to absorb the hits as comfortably as the cartel members can.