"The Americans should know that until now 13 revenge scenarios have been discussed and even if there is consensus on the weakest scenario carrying it out can be a historic nightmare for the Americans," said Ali Shamkhani the secretary of Iran's Supreme National Security Council.
He said that US bases across Iraq are being kept under close surveillance and claimed to know the exact number of personnel and equipment being kept at each.
The Iranian official said that a total of 19 US military bases -- including 11 head bases located east and west of Iran in addition to eight bases in the north and south of Iran -- are already on radar, adding that "we are aware of the conditions of their military equipment and monitoring the smallest developments" there.
'We insist that all troops be withdrawn,' he said. 'If the troops want to dig into the bases, we will destroy the bases in addition to the troops.
'Those who crawl into shelters and close the doors hoping to escape our revenge are unaware that the Islamic Republic will open the door to hell.'
He later added: 'If the US troops do not leave our region voluntarily and upright, we will do something to carry their bodies out horizontally.'
Shamkhani was speaking as tensions peaked following the assasination of Iran's celebrated general by the United States.
Iran has vowed to exact a 'crushing revenge' over the killing, which was expected to ramp up Tuesday after a three-day period of mourning ended.
Islamic Republic has already ripped up what remained of the nuclear deal signed under Obama in the wake of the strike, and its ally in the region, Iraq has voted to kick all US troops out.
Iran's otherwise moderate politician, Foreign Minister Mohammad Javad Zarif went a step further on Tuesday declaring that the countdown has begun for the US's exit from the Middle East.
Israel a target
Earlier head of IRGC, General Hossein Salami made the pledge before a crowd of thousands gathered in a central square in Kerman, the hometown of the slain general Qassem Soleimani, as they prepared to bury him.
"We will take revenge. We will set ablaze a place they like, and they well know where it is," Salami said, drawing the cries of "Death to Israel!"
Israel is a longtime regional foe of Iran and under US President Donald Trump the two countries have drawn considerably closer.
Interestingly otherwise bellicose Benyamin Netanyahu, Israel's prime minister, has been notably quiet since the strike, attempting to distance himself from the US move.
"The assassination of Soleimani isn't an Israeli event but an American event. We were not involved," he reportedly said, according to ministers who spoke with Israeli press.
America on edge
The future of US troops in Iraq too was thrown into confusion when a letter confirming American withdrawal from Iraq was apparently circulated by mistake.
Iraq's parliament voted on Monday to ask US troops to vacate Iraq, 16 years after invading, accusing Washington of violating its sovereignty by attacking Soleimani on Iraqi soil.
'We respect your sovereign decision to order our departure,' said the letter, whose authenticity was confirmed by both Iraqi and US defence officials.
In the letter, US Brigadier General William Seely said the US-led coalition would 'be repositioning forces'."In order to conduct this task, Coalition Forces are required to take certain measures to ensure that the movement out of Iraq is conducted in a safe and efficient manner," said the letter.
It said helicopters would be travelling in and around Baghdad's Green Zone where the US embassy is located as part of the preparations during night hours.
But Pentagon Joint Chiefs Chairman Mark Milley said the letter was a mere 'draft' that was sent by mistake.
However, foreign journalists based in Iraqi capital said they could hear helicopters flying low over Baghdad throughout the night on Monday, according to an AFP report.
Meanwhile amid all this din of rhetoric, where and when Iran chooses to retaliate remains a matter of speculation. Speculations are rife that the targets may include American troops in neighboring Syria and Iraq, American bases in the Persian Gulf or American embassies or diplomats almost anywhere.
As Tehran keeps the Americans and the world guessing for now, Iranians seems to be in no rush to strike back against the United States, possibly enjoying their ability to spread anxiety throughout the West, according to a New York times analysis.
"They seem content to bask in the nationalist surge in their popularity, growing international sympathy and the push to expel American troops from Iraq. I don't think they want to shift the conversation yet," it quoted Sanam Vakil, a scholar of Iran at Chatham House, a research center in London as saying.
The increasingly public vows of direct action on Monday constituted Iran's latest act of defiance to President Trump. Over the weekend the president had repeatedly threatened to retaliate for any attacks against American interests by ordering airstrikes against as many as 52 potential targets, one for each American hostage held after the seizure of the United States embassy in Tehran in 1979.
In response, Iran's moderate president, Hassan Rouhani, on Monday responded with his own numerology. "Those who refer to the number 52 should also remember the number 290," he said on Twitter, a reference to the 290 people killed in 1988 downing of an Iranian passenger airliner by an American warship in the Persian Gulf. "Never threaten the Iranian nation," Rouhani added.