Former German Defense Minister Peter Struck once said "our security is also being defended in the Hindu Kush." At the time, he was justifying the deployment of German and other Western soldiers to Afghanistan. To this day it remains disputed whether this deployment was a failure or a partial success, because the Taliban and al Qaeda were at least temporarily weakened. His analysis of the threat, however, is still valid - and does not only apply to Afghanistan.

It should be clear to all of us today that the security of Europe is also being challenged in Mosul, Tikrit and Ramadi. This past week, one Iraqi city after another has fallen, with almost no resistance, into the hands of radical jihadists. And the fighters of the al Qaeda offshoot Islamic State in Iraq and Syria (ISIS) already have the capital, Baghdad, in their sights.

Hundreds of thousands of people have fled Mosul and the surrounding area in a state of panic, so as not to be at the mercy of a terrorist regime wearing the mask of religion. They are swelling the number of refugees in the region who are moving from place to place, from country to country, many of them eventually seeking refuge in neighboring Europe.

A terrorist state is unacceptable

It seems unlikely that the jihadists will succeed in conquering the whole of Iraq in the near future: Shia and Kurdish militias in the towns and cities with smaller Sunni populations can be expected to put up greater resistance. Also, neighboring states and other regional players such as Iran, Turkey and Israel would not stand idly by if such a scenario seemed likely.

Nonetheless, the whole of Iraq is threatening to descend once more into an endless spiral of violence and terror - which could finally break the country apart. If that were to happen, the world might find itself confronted with a "Caliphate state" of Sunni extremists, armed to the teeth, in parts of Iraq and neighboring Syria. This could swiftly develop tremendous appeal as a military training camp for jihadists worldwide.

The world cannot allow the establishment of any such terrorist state. The Iraqis are entitled to all the help and solidarity we can provide for them in this dangerous and threatening situation, not least because any such state would be a permanent source of danger to Europe. ISIS already has numerous European fighters in its ranks, as well as Sunni extremists from Arab and Asian countries. The man suspected of murdering three people in the Jewish Museum in Brussels had previously fought for ISIS in Syria.

But what can the West do, in view of the complex conflict situation on the ground? Direct military intervention can be excluded for now. After the bitter experience the United States had of its constitutionally dubious military deployment in Iraq, this is an option that is only likely to be used as an absolute last resort. The West should also resist the temptation of allowing itself to be drawn into an alliance of interests with the Syrian dictator Bashar al-Assad. Assad is one of ISIS's main opponents, but he is not the slightest bit better than the Sunni jihadists - rather than beheading his opponents according to supposedly Islamic laws, he terrorizes them with blanket bombing.

More than just military aid

Instead, the first thing Iraq needs is military aid. The United States has already held out the prospect of this. There is no way around the fact that terrorism must be fought with violence - but this cannot be all. It is imperative that any help given to the Iraqi government be linked to political conditions. In particular, considerable pressure must be brought to bear on the Shia prime minister, Nouri al-Maliki, to stop excluding the Sunni minority with regard to the distribution of economic resources and political power. It is scarcely possible that the jihadists would have achieved their recent military successes without at least implicit support from this disadvantaged section of the population.

However, the West must also put political pressure on supposedly "loyal" allies such as Saudi Arabia and other Gulf states - because the backers of ISIS & co. are based in these countries, and they are deliberately fueling the conflict between Shias and Sunnis.