Tehraninfo-iconIraninfo-icon's parliament has unanimously passed a bill designating the United Statesinfo-icon' forces as "terrorists" over the assassination of top military commander Qassem Soleimani in an air attack on the orders of President Donald Trumpinfo-icon in Iraqinfo-icon last week.

Soleimani, the popular head of the Islamic Revolutionary Guard Corps' (IRGC) foreign operations arm Quds Force, was killed in a USinfo-icon drone attack outside Baghdadinfo-icon airport on Friday, ratcheting up tensions between the arch-foes.

Under the newly adopted bill on Tuesday, the entire US forces and employees of the Pentagon and affiliated organisations, agents and commanders and those who ordered the "martyrdom" of Soleimani were designated as "terrorists".

"Any aid to these forces, including military, intelligence, financial, technical, service or logistical, will be considered as cooperation in a terrorist act," the bill said.

The bill is an amendment to a previous motion passed in April last year which designated the US Central Command as a "terrorist organisation" and declared the US a "state sponsor of terrorism". 

Iranian parliaments move attains significance as US troops are deployed across the region. Analysts say Iranian move gives legal cover to any retaliatory action against US bases spread across the region surrounding Iran.

Legislators also voted for $2224 million to be allocated to the Quds Force "to boost their defensive power".

Earlier a top Iranian official said the Islamic Republic was considering 13 'revenge scenarios' in retaliation for the US airstrike that killed General Qassem Soleimani.

Ali Shamkhani, secretary of Iran's Supreme National Security Council, vowed that even if Tehran opted for the weakest option, it will create an 'historic nightmare for the Americans'.

While Shamkhani would not reveal any specific details of the plans, he said all US forces in the Middle Eastinfo-icon are being considered for strikes. 

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.

'We insist that all troops be withdrawn,' he said, according to Iranian newspaper Resalat. '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.'

Iran has vowed to exact a 'crushing revenge' over the killing of Soleimani, which was expected to ramp up Tuesday after a three-day period of mourning ends. 

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.

Britains Daily Mail quoting US intelligence reported that Iran will try to kill one of its top generals in the region in a tit-for-tat slaying. 

One official said the U.S. anticipates a 'major' attack of some type within the next day or two.

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 later today.

"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 Israelinfo-icon!"

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.

He said Israel must not be dragged into the escalating conflictinfo-icon, fearing a direct attack from Iran and it's allies like Hamas in the Palestinian territories and Hizbollah, in neighbouring Lebanoninfo-icon.

The future of US troops in Iraq too was thrown into confusion yesterday when a letter confirming American withdrawal from Iraq was apparently circulated by mistake. 

Iraq's parliament voted on Monday to ask US troops to leave 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.

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.