Visitors and employees attend the Iran Oil, Gas, and Petrochemical International Exhibition on May 6 in Tehran. (Epa-Efe/Rex/Shutterstock)

President Trump’s decision to scrap the Iran nuclear deal and reimpose sanctions has sent global buyers of Iranian oil scrambling to line up other sources of supply.

Saudi Arabia, the world’s largest crude oil exporter and leading force in the Organization of the Petroleum Exporting Countries, issued assurances overnight that it would provide some cushion for the loss of Iranian supplies.

“The kingdom will work with major producers and consumers within and outside OPEC to mitigate the effects of any supply shortages,” the state-run Saudi news agency reported, citing a statement issued by an official in the energy ministry.

But oil traders weren’t convinced. Crude oil prices climbed on Wednesday, with the benchmark West Texas Intermediate grade up $2.19, or 3.2 percent, to $71.25 a barrel for June delivery.

One reason for the skepticism is that over the past two years, Saudi Arabia has been working with OPEC and Russia to hold back exports and gradually run down world inventories to bolster prices. Saudi Arabia has also indicated that it wants to let those stockpiles dwindle further.

Even though prices are at the highest levels in nearly four years, they fall short of what Saudi Arabia needs to pay for domestic subsidies and military costs in the Yemeni civil war. The International Monetary Fund said last week that crude prices would need to average nearly $88 a barrel for the kingdom to balance its budget. Iran needs a $68 a barrel average price at current export levels, the IMF said.

In addition, Venezuelan oil exports have been dropping steadily as a result of internal disarray and U.S. sanctions. And global oil demand is rising as economies recover. The International Energy Agency forecasts an increase of 1.5 million barrels a day in global oil consumption in 2018.

In addition to barring U.S. dealings with Iran, reimposition of the oil sanctions would restrict foreign companies that conduct transactions in dollars or that have operations in the United States.

Yet the details have been vague. One possible reason: The number one and three officials in the Treasury Department’s Office of Foreign Assets Control left the office in the past two weeks.

The Trump administration said that countries seeking waivers from the sanctions would still need to show “significant reductions” in purchases of Iranian oil by November or face penalties. Under President Obama, before the nuclear deal was signed, those reductions were set at around 20 percent. But the administration has not defined what “significant.” means.

“We don’t know whether they will frame it in the same way,” said Elizabeth Rosenberg, a former Treasury expert on terrorism financing and senior fellow at the Center for a New American Security. “The 20 percent figure is not enshrined in written guidance so the Trump folks could use a higher number.”

Analysts estimate that the net effect would reduce the global supply cushion that kept crude oil prices relatively low for the past three years. Theyexpect Iran’s oil exports to drop by between 350,000 and 500,000 barrels a day over the next six months. Iran currently exports about 2.8 million barrels a day.

Some shortfall could be covered by increases in U.S. shale oil output. As prices have risen in recent months, so has drilling activity. The number of active onshore drilling rigs in the United States climbed to 1,011 last week, up 18.5 percent from a year earlier, according to the Baker Hughes rig count.

Goldman Sachs said in a note to commodity investors that the U.S. action “would still end up reducing limited levels of spare capacity in a market already in large deficit.” As a result, the firm said, the Iran “announcement and still rising geopolitical tension in other key oil producing countries like Saudi Arabia and Venezuela all create risk of additional production losses in the face of depleted inventory buffers.”

The firm said it expects prices to rise another 10 percent.

However, some experts say the Trump administration could have trouble curtailing Iran’s oil exports. The biggest buyers of Iranian crude are China, India and Turkey. “They do not have the same interests and may have ways to shield themselves,” Rosenberg said, noting difficulties in getting China to enforce sanctions against North Korea

“If China is unwilling to sanction its companies for dealing with North Korea, will it have an interest in doing that for Iran?” Rosenberg said.

“It’s just another weight on the scale in relations with China,” said Theodore W. Kassinger, a trade expert and partner at the law firm O’Melveny & Myers, said: “The Iranians have had several years to reestablish themselves in global markets. It’s too early to know how established those relationships are. I think there’ll be a lot of pushback on that.”