I've always found it fascinating how jihadist groups have a preoccupation with having their own online English-language magazines.

Al Qaeda in the Arabian Peninsula (AQAP) has "Inspire", while the Islamic State (IS, formerly known as Isis) group in Iraq and Syria has its "Dabiq" magazine. Dabiq is the name of a place in northern Syria that was the site of one of the most decisive Middle East battles in 1516 that gave the Ottoman Empire control over much of the region.

In the recent first edition of Dabiq, a lead article titled The Return of Khilafah celebrates the Islamic State's (IS) declaration of a Sunni Muslim caliphate by its leader, Abu Bakr al Baghdadi.

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Over the last week, al Baghdadi and his IS jihadist fighters have made a dramatic push in the north of Iraq, routing Kurdish forces and extending the territory of their self-proclaimed caliphate.

These battlefield gains have set alarm bells ringing in Baghdad and beyond, especially in Washington.

Yesterday, there were reports that IS fighters had pushed far enough to take control of checkpoints at the border area of the Kurdish semi-autonomous region in Iraq.

Perhaps the most worrying tactical reports to have emerged of IS gains against Kurdish peshmerga fighters is that the jihadists may have captured Iraq's largest dam outside the city of Mosul.

Should this prove to be accurate, and they are in control of the whole facility, the jihadists would effectively have a major weapon of mass destruction at their disposal. As far back as 2006, the US military described it as "the most dangerous dam in the world".

Technically, should they wish, IS would have the ability to close off water supplies to Baghdad or flood the capital city.

Bad news indeed for Iraq's Shia government, which is already struggling to govern and hold back the jihadist advance in Sunni areas of the country.

All this fighting has of course taken a great toll among ordinary Iraqis, especially minority groups. Up to one-quarter of the country's Christians are fleeing after IS overran Qaraqosh in Nineveh province, while some 50,000 members of the Yazidi religious minority were trapped on Mount Sinjar but are reported to have since been rescued.

Many other Yazidis, who are followers of an ancient religion derived from Zoroastrianism and are part of Iraq's Kurdish minority, have fled to the Turkish border and the country's southeastern Sirnak province. They fear extermination at the hands of IS, which dismisses them "devil-worshippers".

"Those who have passports crossed the border, but thousands of people who don't are waiting at the other side," Seyfettin Aydemir, mayor of Sirnak's Silopi district, confirmed yesterday.

Fighters from IS are known to be ruthless and totally uncompromising towards those who do not fit their extremist doctrines.

Eyewitnesses in Qaraqosh yesterday said IS militant were taking down crosses in churches and burning religious manuscripts. Throughout the month of Ramadan the territorial gains made by the IS offensive in both Iraq and Syria have been relentless.

This land grab is something they have been keen to reflect in the latest edition of Dabiq, the title article of which is The Flood.

Using the example of the prophet Noah, the group argues that Muslims have the choice of either supporting IS or perishing as the group overwhelms the earth like Noah's flood.

The article also underlines the groups's recent military successes and claim it to be the true leader not only of the jihadist world but of all Muslims.

While the world's attention, understandably, has been focussed on the Israeli onslaught in Gaza, the IS takeover in much of western Iraq and increased control in rebel-held areas of Syria has slipped a little from the news radar.

In Syria yesterday IS fighters stormed one of the Syrian Government's last outposts in the northern province of Raqqa. The group's hardened fighters, many of them foreign, have been chipping away at government redoubts in the area since last month. Now Raqqa has joined the raft of towns and cities in both Iraq and Syria that have fallen under the control of the jihadists.

As if this was not enough to worry about, there are signs now that IS have also moved into Lebanon, which would mark their furthest progress yet across the region.

Reports indicate that in the Lebanese town of Arsal, jihadist fighters, officially from the al Nusra Front, have made their presence felt and are battling Lebanese troops.

According to the veteran Middle East reporter Robert Fisk, these al Nusra fighters have already expressed their allegiance to IS and leader Abu Bakr al Baghdadi's caliphate.

Over the past 15 years the Lebanese army has twice fought and defeated jihadist rebellions inside the country. If statements by senior Lebanese Government and military chiefs are anything to go by, though, the takeover of Arsal by the jihadists was a long time in the planning and most likely part of an IS strategy to extend its influence and caliphate.

For now, IS fighters led by Abu Bakr al Baghdadi continue to flood across a swathe of territory from the Tigris towards the Mediterranean.

One can only guess at what it will take militarily to halt their destructive advance. What Washington does next will be well worth watching.