Fears of open military conflict in the Middle East rose on Thursday night after the US prepared limited strikes on Iran following the downing of a US surveillance drone, according to the AP.
Tehran said the drone was flying over Iranian airspace, which Washington denies.
This incident comes after tensions between the two countries have risen after oil tankers passing the Iranian coast were damaged. The US blames Iran, which denies involvement.
Iran state media said the drone was brought down over the southern Iranian province of Hormozgan — located on the Gulf — with a locally made 3 Khordad missile. But a US official said the drone was a Global Hawk that was downed in international airspace over the Strait of Hormuz.
Lieutenant General Joseph Guastella, the top US Air Force commander in the Middle East, told reporters the drone was shot down at about 34 km from the nearest point of land on the Iranian coast.
US Central Command later posted a tweet with a map of what Guastella said was the drone’s flight path showing it outside of Iran’s territorial waters. "This was an unprovoked attack on a US surveillance asset that had not violated Iranian airspace at any time," he added.
Iranian Foreign Minister Mohammad Javad Zarif said on Twitter the aircraft had taken off from the United Arab Emirates "in stealth mode & violated Iranian airspace."
The downing of the drone served as a stark reminder of the risk of military conflict between the US and Iran as Trump pursues his "maximum pressure" campaign of economic sanctions and the buildup of US military forces in the region.
What have been the reactions from key players?
Trump played down the downing of the drone on Thursday, saying he suspected it was shot by mistake and “it would have made a big difference” to him if the remote-controlled aircraft had been piloted.
While Trump seemed like he didn’t wish to escalate the situation with Iran, he also added: “This country will not stand for it”
"I think probably Iran made a mistake. I would imagine it was a general or somebody that made a mistake in shooting that drone down," he told reporters at the White House.
"We had nobody in the drone. It would have made a big difference, let me tell you, it would have made a big, big difference" if the aircraft had been piloted, Trump said after a meeting with Canadian Prime Minister Justin Trudeau in the Oval Office.
"It's hard to believe it was intentional if you want to know the truth," he added, saying it could have been carried out by someone who was acting "loose and stupid," and calling the incident as "a new wrinkle ... a new fly in the ointment."
But Democrats in Congress were worried Trump might start a war with Iran over the incident.
US House of Representatives Speaker Nancy Pelosi said Washington was not looking for a war with Iran and should "do everything in our power to de-escalate."
But Senate Republicans were also eager to de-escalate the situation. Senate Majority Leader Mitch McConnell, told reporters: "The administration is engaged in what I called measured responses."
On Thursday, Iran called the sanctions "economic terrorism", insisted the drone flew over its airspace and said it was taking the case to the United Nations to prove the US was lying about the aircraft being in international waters.
Iran's UN ambassador Majid Takht Ravanchi said in a letter to the UN secretary-general that the drone had entered Iranian airspace despite "repeated radio warnings" and was shot down by Iran under the UN Charter that allows self-defence action "if an armed attack occurs".
An Iranian Revolutionary Guards statement said the drone’s identification transponder had been switched off “in violation of aviation rules and was moving in full secrecy” when it was downed, reported Iranian state broadcaster IRIB.
"Our airspace is our red line and Iran has always responded and will continue to respond strongly to any country that violates our airspace," Ali Shamkhani, secretary of the Supreme National Security Council, told Iran's Tasnim news agency.
Saudi Arabia, Washington’s main ally in the Gulf region said Iran had created a serious situation with its “aggressive behaviour” and that it would consult other Gulf nations to discuss the next steps to take.
A US envoy for Iran met with Saudi Arabia's deputy defence minister Prince Khalid bin Salman in Riyadh on Friday.
In a tweet, the minister said they discussed the recent attacks in the region and affirmed Saudi Arabia's support for the US campaign to pressure Iran.
European diplomats have said more evidence is needed to pinpoint responsibility for the tanker strikes.
Senior officials from Iran, France, Germany, Britain, China and Russia will meet on June 28 in Vienna to discuss ways to save the 2015 nuclear accord, the EU said on Thursday.