Today, the 13th anniversary of the 9/11 attacks which killed over 3000 people and launched us into what seemed to be a clash of civilisations, we seem to be at a tipping point in the impending battle against the Islamic State (IS). At some point, Barack Obama will need to make a decision on whether to launch military action against them, and Britain (or what is left of it after the referendum next Thursday) will probably have to follow behind.

Some argue that IS only exists and thrives because of the instability that the region was thrown into by the reaction to 9/11, led by the USA and including the invasions of Iraq and Afghanistan. Well, whatever is the cause of their advance, we are in a position now where we have a group intent on establishing a caliphate and forcibly converting or killing anyone who doesn’t want to join them. So, given the Iraqi army, the Kurds and the Free Syria army don’t seem capable of dealing with IS, their weaponry and money, we in the West are going to have to stand up to be counted. I’m not sure there is any alternative.

There are two central theories in international relations, one is realism and the other is liberalism . Proponents of realism argue that the world is a harsh and dangerous place in which relative power between states matters. The primary role of the state is self-preservation so there is a moral responsibility for a state to protect itself. Those who tend towards liberalism argue that realism is outdated in this interconnected and globalised world in which we are linked by a system of complex interdependence, essentially meaning that our economic and social connections mean we should solve conflict by working together, not by military means.

It is possible to make a case for liberalism when it comes to countries like Russia and Saudi Arabia, despite our need to hold our nose when we do so, but with Islamic State, their advance, particularly if they established a stronghold in the East of Syria and a West of Iraq, is dangerous for all of us. They are not interested in trade links, not interested in social links, just in dominating all, and attacking anyone who won’t join them. They are soon to be exporting terror back to Britain, as once they have their stronghold the Britains who have been fighting for them will come back, trained, to Britain. Hence the link to 9/11. So, realism needs to take over.

So what does this mean? Does it mean we join together with a President Assad of Syria to fight IS? I would hope not, because we would then be stuck in his debt, and after the hundreds and thousands of moderates he has killed to keep power I’m not sure we want to be. Do we work with Vladimir Putin and Russia? Not unless we are prepared to recognise Crimea, illegally annexed earlier this year, as part of Russia. Do we join together in solidarity with the Mullahs of Iran? Only if we are comfortable with them becoming a fully fledged nuclear power.

If we can use air strength, the area where Islamic State is weakest, to provide cover for the Iraqi and Kurdish army to send IS back to Syria, then help the Free Syria army to overcome them once in Syria, we have a chance to achieve the aim of neutralising IS without making dirty compromises with anyone. Because the Iraqi Government has asked us to intervene, we don’t need to go through the UN, which helps, and given the Islamic State are essentially an invading force in a foreign country, there is moral force in stopping them.

The only problem for us Brits is that if Scotland leaves us, we become denuded of part of our most effective fighting forces, and this may lead to us not being part of any solution. Many fear that the UK without Scotland will lose its place on the UN Security Council and NATO, meaning whatever action takes place over the next year or so will happen quite literally over our heads. There is no international issue or problem that is made better if Scotland leaves the UK. Just something else to think about over the next seven days.