ISIS fighters at a checkpoint in the northern Iraq city of Mosul
[Representational Image] Iraqi forces have reportedly retaken the city of Fallujah from the Islamic State (ISIS) group with a senior commander declaring on Sunday that Fallujah is now "fully liberated" after a month-long fight against the terrorist organisation. Picture: Isis fighters at a checkpoint in the northern Iraq city of Mosul in June 2014.Reuters

A day after the first batch of US Marines arrived in Iraq, the Islamic terrorist group invading the country posted a picture posing with a decapitated head and issued another threat to America.

The Al Qaeda off-shoot has let loose a reign of terror in Syria and Iraq and ultimately wants to establish an Islamic state in the countries, after which it wants to go after US for 'payback.'

In a rather gruesome Twitter post on Thursday, the Islamic State of Syria and Iraq(ISIS) militants posted a picture holding a decapitated head of a Shia fighter. The picture was posted with a hashtag #CalamityWillBefallUS.

The post features a dozen armed masked-men standing around the body and while one of them is a holding the head, others have their feet on the body. The message on the post said that if America does not stop its bloodbath in Iraq, the ISIS will stamp out Americans.

Oh America, we will make your people beneath our feet, if not stop the bloodshed #CalamityWillBefallUS

— [ بُثينة الأنصارية ] (@Bq_A4) June 25, 2014

Since the arrival of the American troops, the ISIS has increased its online propaganda against the US government.

The crisis in Iraq has worsened after the Syrian government allowed Israeli warplanes and rockets to attack ISIS areas inside Iraq.

The initial reports had blamed US Drones for the the attacks carried out in Iraq's western border areas under ISIS control, however, Pentagon has vehemently denied any involvement.

The ISIS affiliates are now threatening to carry out a 9/11 like attack in US, while another has warned that the group will target US embassies world-over with car bombs.

Here are few of the ISIS threats issued on Twitter:

I know approximately 20000 fighter form ISIS Ready for explosion in USA #CalamityWillBefallUS — الأزدي (@Nayef507) June 26, 2014

If you touch #Iraq with harm : then wait for a repeat of explosive day : 9/11 !! #CalamityWillBefallUS #ISIS

— أبو الدرداء (@AbuYazidMuawiya) June 26, 2014

if America attacks Iraq; every American embassy in the world will be exposed and attacked with car bombs. #CalamityWillBefallUS — ام القاده #باقية (@atkh1396) June 26, 2014

#CalamityWillBefallUS Sure send your advisors you filthy colonialists, but this will happen

— Abdul-Malek (@truthsMaster) June 26, 2014

US under ISIS Threat?

The threats issued by the ISIS echos the alarm that the US Congressional report raised claiming that ISIS will ultimately target US soil after taking over Iraq and Syria.

The report that was released on 20 June noted that ISIS also known as ISIL has the intent to attack the United States and is recruiting and training individuals to do so, noted The Washington Times.

The report besides taking inputs from the intelligence agencies also took in the direct threat issued by ISIS leader Abu Bakr al-Baghdadi who had said: "Know, O defender of the Cross, that a proxy war will not help you in the Levant, just as it will not help you in Iraq. Soon, you will be in direct conflict — God permitting — against your will."

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