If there was any doubts that Jordan is at war the arrest of the Deputy Leader of the Jordanian Muslim Brotherhood (JMB), Zaki Bani Irsheid, should dispel them. Bani Irsheid's crime was to write a ludicrously over the top criticism of the Emirates on his Facebook page, accusing the UAE of being "the first sponsor of terrorism". The Government response was to pick him up and drop him in jail with the numerous other oppositionists they have arrested in recent months.

Two years ago, he may have got away with it. After all, the JMB is Jordan's pre-eminent opposition party, an activist Islamism party deeply entwined in the political fabric of the country. But today the battle lines are drawn, the lead-up set by King 'Abdallah's recent speech about the civil war in Islam between moderation and extremism. 'Abdallah sees himself and his Emirati backers on one side of the equation, and while they never were before, the JMB are now on the other. The language used to justify the arrest was telling; Bani Irsheid's arrest was not a matter of politics, it was a matter of security. Today, you are either with the Jordanian government and its Gulfi backers, or you are very much against them, writes Charlie Pratt.

It would be trite to be too critical. Jordan faces internal and external threats that could easily overwhelm it, parked as it is on the border of two very real wars in Syria Iraq where ISIS and other extremist groups bed down. Today, approximately 2,000 Jordanians are fighting in these conflicts, and there is a powerful radical Salafi community at home, especially in poor Southern towns like Ma'an. 'Abdallah's support to the fight against ISIS/ISIL and others has made him an apostate in the eyes of these men. The King has held his nerve and risen to the mantle of a wartime leader, but when these men search for his death and the downfall of his system, it is little surprise that he has reached for the uniform and reverted to a militarised rule.

But if John Kerry is right, and ISIS is slowly being defeated, the bigger question is what comes when the threat is contained; can Jordan move back from the overwhelming security-based politics 'Abdallah has enacted? Or will it remain a locked down country hostile to political opposition? And in either scenario, how will the government deal with the reforms that were so desperately needed prior to the ISIS crisis?

The answers to those questions is why the arrest of Bani Irsheid is so critical, for his case will tell us much about the trajectory of Jordanian politics and society. Let us be clear, Irsheid showed his stupidity and his own contemptible prejudices in his article. But the Brotherhood are still an important, legitimate voice for a powerful groundswell of conservative Sunnis from across the Kingdom. 'Abdallah has been forced to respect them, even offering them placatory seats in the Senate following the protests of 2012, to buy acqueisence from this lobby. They are entwined in the political fabric of the country, and a key part of any necessary reform. Prime Minister Ensour has made it clear that his trial is now a judicial matter that the government cannot interfere in, but if they are criminalized, so are a large section of Jordanian society.

In this sense, it is not ISIS that will decide Jordan's fate, but King 'Abdallah himself. The military decisions he is making are faultless, and though 'Abdallah is widely loved and trusted by his people, the toll of conflict is falling heavily on society. There are those who contest his rule, particularly as there has been no significant movement on domestic political, nor economic, reform in the last year. The economic conditions are worsening for his country, and the calls for political reform – either for a more representative country, or for a more conservative one – remain. The criminalisation of opposition will only worsen this trend, preventing any legal outlet for criticism of 'Abdallah's rule. 'Abdallah may be able to control his military destiny, but he seems less in control of his domestic politics. Just as Egypt is beginning to find out, the home front is as important as the Iraqi border, or the glass offices of Emirati seniors - it is where the greatest fight for the future of Jordan is being faced.

The challenges Jordan faced before the ISIS crisis – political, economic and social – have only been briefly suspended by a supreme effort of national will. They will be more pressing by some distance when they do return. In this sense, 'Abdallah's job is often impossible. His country is not an economic powerhouse, and is buffeted by the flow of politics and economics that roils across the Levant. Like the wider Middle East his country is schizophrenic, various elements of its society torn between liberalism and moderation, conservatism and Islamism. In turn, 'Abdallah has traditionally played a fine balancing act between progressivism and conservatism, autocracy and democracy. But in the febrile atmosphere generated by the emergence of ISIS that balancing act has become near impossible. His recent speeches in military uniform, alongside the arrest of Bani Irsheid, show how far the balance has tipped. In the future, he may find out that the greatest challenge he faces is not learning how to be a military leader, but remembering how to be a political one.