An additional fact to consider: Tariffs would make USA oil uncompetitive in China. United States crude futures added 34 cents, or 0.5%, to $74.14.
US crude CLc1 slipped 2 cents to $72.92.
Although the current list of products caught in the tariff war does not include energy-related products, oil traders continue to monitor the events because Beijing has threatened a 25-per cent tariff on U.S. crude imports.
Trump's trade war with China - which like the Iran conflict was predicated on the not entirely inaccurate argument that the US was getting the short end of the stick with regards to business relations - is another example in which pundits are predicting rough road ahead, despite compelling arguments from minority voices that the dispute will eventually resolve in the Americans' favour.
"The Chinese have to do the tit-for-tat, they have to retaliate", said John Driscoll, director of consultancy JTD Energy, adding that cutting USA crude imports was a means "of retaliating (against) the United States in a very substantial way".
West Texas Intermediate rose 61 cents to settle at $73.55, while Brent declined by 39 cents to $77 per barrel.
China has said it will impose tariffs on 545 US goods in return. In response to this, members of OPEC reportedly agreed to produce an additional one million barrels of crude oil on a daily basis to keep the prices stable on the market.
Army reportedly giving immigrant enlistees the boot
But several foreign-born reservists and recruits have reportedly been discharged without any real explanation. Donald Trump's administration added even more hurdles, creating a backlog within the Defense Department.
He added that his refinery had canceled US crude imports and would switch to Middle East or West African supplies instead.
Energy consultancy FGE warned on Friday of looming supply shortages due to USA sanctions against Iran, and because of disruptions elsewhere.
Even if the US government grants some waivers to allies, FGE estimated 1.7 million to 2 million bpd of crude and condensate would be cut out of markets once its sanctions are implemented.
United States investment bank Jefferies said on Friday it expected a decline in Iranian exports "well in excess" of 1-million barrels a day due to the U.S. sanctions.
Last Friday, unnamed sources told Reuters that the Korean government had pressured refiners into suspending orders for July shipments of Iranian crude, which is the first time this has happened since 2012.
Oil consultancy FGE agrees, noting that China is unlikely to heed President Trump's warning to stop buying oil from Iran.
Top exporter Saudi Arabia told OPEC it raised oil output by nearly 500,000 barrels per day last month, OPEC sources said, a sign Riyadh wants to make up for shortages elsewhere and dampen prices.