The more obvious catalyst over the past week was the U.S....

The more obvious catalyst over the past week was the U.S. withdrawal from the Iran nuclear deal, putting a sizable chunk of Iranian supply at risk, Most importantly, The underlying fundamentals are bullish: the supply/demand balance is tighter than at any moment in recent memory, with demand expected to outpace supply for the rest of the year. Global inventories are back down to the five-year average, and falling. Because data is published on a lag, the market could overtighten before OPEC realizes it.

https://oilprice.com/Energy/Energy-General/Higher-Oil-Prices-Look-Likely.html