Benchmark prices for American crude oil cracked $70 a barrel on Monday, the first time it has climbed that high since 2014, as investors factored in the prospect of President Trump pulling the United States out of an international agreement that eased sanctions on Iran in exchange for restrictions on its nuclear program.
Mr. Trump, who faces a deadline of May 12 to decide whether to withdraw from the Iran deal, has threatened to do so unless Britain, France and Germany agree to make wholesale changes to the agreement.
The fear among investors is that a United States exit from the deal would probably lead to new oil sanctions being imposed on Iran, the world’s fifth-largest producer of crude oil last year, further curtailing a global supply that is already relatively tight.
The Organization of the Petroleum Exporting Countries — the powerful cartel of oil-producing nations led by Saudi Arabia — has restrained production since last year while making common cause with oil-dependent Russia to keep a cap on global supply and to prop up prices. The flow of oil to the global market has been further constricted as a result of the political and economic crisis plaguing Venezuela, another major producer of crude, in recent years.
A boom in production in the United States has helped offset some of the tightening in recent months. But higher prices elsewhere have prompted American producers to sell on the global market, driving oil exports to record highs and pulling domestic oil prices higher.
The cost of a gallon of gasoline in the United States has followed suit, with the national average price for unleaded regular climbing above $2.80 in recent days. Energy companies seem poised to benefit from the surge. The energy sector led the broader Standard & Poor’s 500-stock index higher Monday, rising by more than 2 percent, compared with the broader index, which was up less than 1 percent.