- Oil prices rises as the United States re-introduces sanctions against major crude exporter Iran.
- A first batch of U.S. sanctions against Iran officially came into effect at 12:01 a.m. U.S. Eastern time on Tuesday.
- Tuesday also marks the halfway point in a 180-day wind-down period before sanctions on Iran's energy industry and oil exports snap back into place.
Oil prices rose on Tuesday after U.S. sanctions on Iranian goods went into effect, intensifying concerns that sanctions on Iranian oil, expected in November, could cause supply shortages.
The first U.S. sanctions against OPEC member Iran officially came into effect at 12:01 a.m. EDT. These sanctions did not include Iran's oil exports. The country exported almost 3 million barrels per day (bpd) of crude in July.
The reimposed sanctions target Iran's U.S. dollar purchases, metals trading, coal, industrial software and its auto sector. U.S. sanctions on Iran's energy sector are set to be re-imposed after a 180-day wind-down period ending on Nov. 4.
"It is a reality check that this is happening and that Iran's oil exports will be hurt when the oil sanctions hit it in November," chief commodities analyst at Commerzbank Bjarne Schieldrop said.
"The re-imposition of U.S. sanctions on Iran remains the key (price) driver in the near-term. Supply losses could range from 600,000 to 1.5 million bpd," ANZ said on Tuesday in a note to clients.
As a result, the bank said, "the oil market should remain tight, despite OPEC increasing oil production to offset losses elsewhere."
President Donald Trump tweeted on Tuesday that the sanctions were "the most biting sanctions ever imposed," although those sanctions were originally devised and deployed by the Obama administration.
"Anyone doing business with Iran will NOT be doing business with the United States," he added.
@realDonaldTrump: The Iran sanctions have officially been cast. These are the most biting sanctions ever imposed, and in November they ratchet up to yet another level. Anyone doing business with Iran will NOT be doing business with the United States. I am asking for WORLD PEACE, nothing less!
Many European countries, China and India, oppose the sanctions, but the U.S. government said it wants as many countries as possible to stop buying Iranian oil.
"The market continues to price in geopolitical risk from the reimposition of sanctions by the U.S. on Iran," said Gene McGillian, vice president of market research at Tradition Energy in Stamford, Connecticut. "The reports that Saudi Arabia's production actually dropped in July continue to provide support for the market."
Saudi Arabia's crude production dropped about 200,000 bpd last month, two sources at the Organization of the Petroleum Exporting Countries said on Friday, despite a pledge by the Saudis and top producer Russia to raise output from July, with Saudi Arabia promising a "measurable" supply boost.
Also supporting prices were a weakened dollar, McGillian said. The dollar index was trading 0.2 percent lower. A weak dollar can lift the price of commodities, like oil, that are priced using the currency.
U.S. crude stockpiles were also expected to have dropped last week. Data from the American Petroleum Institute for U.S. inventories is due later on Tuesday at 4:30 p.m. EDT, followed by the government's report on Wednesday morning.
Some analysts warned that a global heat wave could also affect oil demand.
Much of the northern hemisphere has been gripped by extreme heat this summer, pushing up demand for industrial and residential cooling. This mostly impacts demand for power fuels such as thermal coal and natural gas.
"With global demand remaining healthy and the global heatwave increasing oil demand, I think prices will remain well-supported in the near term," Hussein Sayed, chief market strategist at FXTM, said.
But U.S. bank JPMorgan said a warmer-than-usual fourth quarter could stem from a potential El Niño weather pattern that "can cause droughts, flooding and other natural disasters across the globe, including heatwaves in the U.S. that affect commodities."
"Past instances of El Niño have resulted in sharp drops in U.S. residential and commercial heating oil demand and prices," it said.
— CNBC's Tom DiChristopher contributed to this report.