THE DEATH

"And when the Lamb broke the fourth seal, I heard the fourth living being say,  Come!' And I looked up and saw a horse whose color was pale green like a corpse. And Death was the name of its rider, who was followed around by the grave. They were given authority over one-fourth of the earth, to kill with the sword and famine and disease and wild animals" (Revelation 6:7-8 NLT).

THE SPREAD OF TERROR AND VIOLENCE

I have seen the wicked in great power, and spreading himself like a green bay tree. Yet he passed away, and, lo, he was not: yea, I sought him, but he could not be found. (Psalms 37:35-36)

Green (Arabic: أخضر) is considered the traditional color of Islam. The Arabic word for "greenness" is mentioned several times in the Quran, describing the state of the inhabitants ofparadise.

Green was used as the color of the banners of the historical Fatimid Caliphate. The Fatimid banner was in use until 1171, and thus during the first century of the crusades, and by this way has taken influence on Christian heraldry, where the tincture vert was very rarely if ever used for the field (background) until the end of the Middle Ages (indeed the term sinople used to signify a reddish color until the 14th century, and only after ca. 1400 did it change its meaning to refer to green as a heraldic tincture).

For they speak not peace: but they devise deceitful matters against them that are quiet in the land.(Psalms 35:20)

Islamist militants have declared an Islamic "caliphate" in an area straddling Iraq and Syria, trumpeting the declaration in several videos.

One slick video, mostly in English, features a bearded fighter with an AK-47 on his back, explaining the new caliphate.

"This is not the first border we will break, we will break other borders," a jihadist from the Islamic State in Iraq and the Levant (Isis) warned in the video called End of Sykes-Picot, a reference to the agreement between France and Britain that divided up the Ottoman empire territories after the first world war.

Later the fighter pledges that jihadists will free Palestine. "We are not here to replace an Arab cahoot with a western cahoot. Rather our jihad is more lofty and higher. We are fighting to make the word of Allah the highest," the spokesman said.

He is filmed showing abandoned Iraqi army badges and vehicles left by fleeing soldiers. "There is no army in the world that can withstand the soldiers of Islam," he said.

The video features about a dozen men in a cell said to be captured troops and border police. A building, said to be a police station, is shown being blown up, as well as US-made Humvees captured from the border police. "Look how much America spends to fight Islam, and it ends up just being in our pockets," the spokesman taunted.

Isis, a breakaway group from al-Qaida, is notable for its hardline anti-Shia sectarianism, declaring Shia Muslims and other rivals as heretics that deserve death.

Abu Mohammed al-Adnani, an Isis spokesman, defined the Islamic state's territory as running from northern Syria to the Iraqi province of Diyala north-east of Baghdad, a vast stretch of land straddling the border that is already largely under Isis control. He also said that with the establishment of the caliphate, the group was changing its name to the Islamic State, dropping the mention of Iraq and the Levant.

"The legality of all emirates, groups, states and organisations becomes null by the expansion of the caliph's authority and the arrival of its troops to their areas," he said in an audio statement posted online, AP reported. "Listen to your caliph and obey him. Support your state, which grows every day."

A member loyal to the Islamic State in Iraq and the Levant (ISIS) waves an ISIS flag in Raqqa, Syria. Photograph: Reuters

Adnani said the group's chief, Abu Bakr al-Baghdadi, is the leader of the new caliphate and called on Muslims everywhere, not just those in areas under the organisation's control, to swear loyalty to him.

Baghdadi has been disowned by al-Qaida's leader, Ayman al-Zawahiri, after al-Baghdadi ignored al-Zawahiri's demands that the Islamic State leave Syria.

Since the Ottoman collapse, Sunni Islam has lacked an internationally recognised clerical hierarchy and senior figures generally hold authority within a single country. Among the most prominent of these is the Grand Mufti of Egypt, whose spokesman dismissed the new caliphate in Iraq and Syria as an "illusion".

"What they called the Islamic caliphate is merely a response to the chaos which has happened in Iraq as a direct

result of the inflammation of sectarian conflict in the entire region," Ibrahim Negm said in Cairo.

Another video called Breaking of the Borders showed Isis fighters killing Iraqi border guards, Reuters reported.

Meanwhile, the Syrian Observatory for Human Rights, a monitoring group, said Islamic State fighters crucified eight men said to be rival rebel fighters in the town square of Deir Hafer in Syria's Aleppo province on Saturday as a warning to others.

An analyst said the declaration of a caliphate by the Islamic State posed a huge challenge to al-Qaida.

"Put simply, Abu Bakr al-Baghdadi has declared war on al-Qaida," said Charles Lister, a visiting fellow at the Brookings Doha Centre. "While it is now inevitable that members and prominent supporters of al-Qaida and its affiliates will rapidly move to denounce Baghdadi and this announcement, it is the long-term implications that may prove more significant.

"Taken globally, the younger generation of the jihadist community is becoming more supportive of Isis, largely out of fealty to its slick and proven capacity for attaining rapid results through brutality."

The Islamic State's declaration came as the Iraqi government tries to claw back some of the territory gained by the jihadists and disaffected Sunnis.

On Sunday, Iraqi helicopter gunships struck suspected insurgent positions for a second consecutive day in the northern city of Tikrit, the predominantly Sunni hometown of former dictator Saddam Hussein. The insurgents appeared to have repelled the military's initial push and remain in control of the city.

Israel's prime minister, Binyamin Netanyahu, has voiced support for Kurdish statehood, calling for the establishment of an independent Kurdistan as part of a broader alliance with moderate forces across the region. The US, however, has said Iraq should stand together in the face of Isis and other jihadists.