Concerns over new U.S. sanctions against Iran sent oil prices higher for the second day on Thursday, pushing them to new multi-year highs after gains over 3 percent during Wednesday's U.S. trading session. U.S. WTI futures were up 0.77 percent as of 1:05 p.m. HK/SIN on Thursday, to trade at $71.69 per barrel. Brent crude futures hit a high of $77.80 per barrel, a price not hit since November 2014, before declining slightly to $77.76 per barrel in the early afternoon.

Despite very vocal opposition to U.S. President Donald Trump's withdrawal from the Joint Comprehensive Plan of Action (JCPOA) from leaders in the United Kingdom, Germany and France, analysts are concerned that no country will really be able to do anything to stop the sanctions. In other words, in an escalated showdown between Iran and the U.S., the U.S. continues to hold the upper hand on both diplomatic and military fronts.

Past U.S. sanctions against Iran demanded a restriction of 1 million barrels per day of oil exports from Iran. Some analysts believe that this will be the starting point for the new sanctions that President Trump is planning to implement, even though he hasn't yet mapped out his actual plan thus far. If this happens, oil could surpass $90 per barrel.

Also pressuring oil prices are lowered production by OPEC countries and increased global demand. Additionally, if the U.S. sanctions against Iran escalate tensions in the Middle East additional factors could curtail production further. One factor that could push prices lower is the soaring U.S. output which has, until now, undermined OPEC's efforts to boost prices. U.S. crude production hit a record high of 10.7 million barrels per day last week, a 27 percent production increase since mid-2016.