By studying the terrorism in its native context, and by carefully isolating it, if it is possible, from other forms of political violence.

What a great but tough question. Three things in my view:

1. Give serious international effort to addressing long running global injustices (Israel/Palestine, Kashmir, etc) by being genuinely creative and accepting that compromises need to be made in favour of local communities not nation states, as has partly happened in Ireland's peace process;

2. Provide a more balanced and fully secular education to young people about history, politics, religion, geography in order to widen people's knowledge base and enable more tolerance;

3. Governments such as my own need to stop pandering to and indulging religious interests/interest groups (such as so called 'faith schools' in the UK) and help move religion into the private realm and out of the public sphere. The Ottoman empire tradition did multiculturalism so much better than anyone does today...

Simple!

In my opinion there are several measures that need to be taken. These are some of them:

1-  Stop supporting terrorism groups by all countries no matter the reasons used by them in support of their activities.

2-  Cut all flow of weapons, munitions, resources and people to all terrorism groups by all countries.

3-  Declare the support of terrorism activities by a person a criminal activity by all countries.

4- Close all schools and training camps and institutions that are used to teach terrorism activities in all countries.

5- Close all internet home pages associated in way or another with terrorism groups or support terrorist activities in all countries.

6- Isolate all countries that openly support terrorist groups or activities.

7- Establishment of an international military forces to combat all terrorism groups located in any country that support terrorist activities.

There cannot be any reason for justifying terrorism, which is a menace to human civilization. Terrorists are fanatics, who try to justify their inhuman acts by diversionary tactics.Terrorists do not belong to any particular race or religion; they are simply terrorists. Terrorists must be dealt with iron hand. International community must unite against terrorism, impose economic sanction on the country that supports / breeds terrorism. Terrorists would find one reason or other to propagate terrorism. The international community must isolate the terrorists and act firmly against them, wherever they are.

Stop selling weapons to criminals. Stop selling weapons!!! If there was no arms trade there would hardly be the kind of atrocities to innocent children in the world. By providing arms the US and every other country is equally guilty with the criminals. Seems like such a no-brainer to quote your kids, so why are leaders utterly incapable of handling something clearly, absolutely necessary?

Unfortunately, terrorism is a weapon of the weak when other remedies appear to be irrelevant or invidious. It is driven, in part, by the perception/reality of marginalization as an institutional obstacle to self-fulfillment by those who are marginalized.

It is also a response to violent oppression and the terror inspired by such oppression.

Its solution lies in the articulation and development of strategies for inclusion - and the necessary intelligent leadership for the development of such strategies. 

Stop funding them...to start!

 I am tempted to give a politically incorrect answer to this question and everyone knows what it is: by bombing them. IS is not an oppressed tribal group resorting to terror as the last resort. It is a war to establish Caliphate. International terrorism is not a weapon of the weak. (Re. Fraser)

The measures mentioned above are useful to stop further spread of it. But the immediate solution is bombing.

Then stop fund flow, stop selling small arms to terrorists (freedom fighters at this stage) and then big ones to the governments (democratic govt threatened with extinction at this stage).

Now it is proved beyond doubt that creating irregular army for whatsoever "noble" cause boomerangs. Big powers need to understand that short term geopolitical gains may prove to be very painful in the long run. 

If there is a war by IS to establish a caliphate, one way of assessing the phenomenon is to ask the simple question - is that goal a signal that existing religious/political  governance structures are in question among some adherents of Islam?  

I would recommend a reading of press reports on the case at the International Criminal Court in the Hague where an Islamic extremist - Ahmad al-Faqi al-Mahdi - awaits sentencing for destroying holy sites in the ancient city of Timbuktu in Mali. As a Wahhabi, " His alleged orders were to attack the shrines of Sufi saints, break down a mosque door that locals believed had to stay shut until the end of the world, and burn priceless manuscripts from Timbuktu’s archive." (The Guardian, 8/21/2016)

There has been increasing conflict in recent decades among adherents of Islam in a  variety of contexts  - and the destruction/defilement of holy sites is certainly not a sign of strength. It is a tactical approach to promoting a challenge to existing authorities.

The 1979 attack on the Grand Mosque in Mecca was a major catalyst for the rise of contemporary Islamic radical movements but the attackers/militants in 1979 were successfully overcome by the Saudi government  with Western military assistance.

Existing political structures are under attack by a section of Islam which do not believe in the political system that the world has evolved in various forms. Sufism is under attack in many parts of Islamic world because it lacks the feudal desert character.

One need to trace radical Islam not in the philosophy of Islam or the sects like Sufism, which is a by-product of traditional Islam meeting the fertile remnants of Babylonian culture, but in the feudal desert character of its origin. The rudimentary 'dos and donts' of traditional belief acquired the backing of philosophy from those who were their opponents.   

Attack in the Sufi shrines only shows that political unification of the radicals is under threat from spiritual understanding of the teachings of Muhammad or Ali or other Islamic philosophers.    

Dear colleagues, why you are reflecting only »Islamic terrorism«. In my opinion, this matter needs reflection of the basic terms we are talking about. Perhaps to change the question to »how to curb/stop international state’ terrorism«; perhaps we, as scientists, should start to think the terrorism of “contemporary Islamic radical movements” not as »international terrorism« but as an answer to »international state' terrorism«, as a kind of revolution as a substitution for war, and war, on the other hand, as revolution against a part of the international order (Geoffrey Blainey, The Causes of War, 3rd ed (NY: Free Press 1988) pp.ll-12); or modem war as »an international revolution or a revolt against a part of the international order, which turns into an unbearable nation or group of nations (E. Dickinson after Q. Wright, A Study of War (U. of Chicago Press 1942) p. 40). Not at last, what happened with that what we think as »international order« after deconstruction, desecuritization and destroying state (not all) as the unit of the international order? Isn't a result of that a destroyed state' international order? And, what we are, as political geographers, talking/thinking about?

Terrorists do not have any religious dimensions, but have psychological dimensions, which engulf the rational thinking and radicalize them to an illusory faith, that forces them to adopt destructive measures, in order to realize the delusion.  These psychic people are menace to the civilized world.  Today, we are seeing group of fanatics causing harm to humanity, earlier world had seen worst dictators causing genocide.

may I refer you to my paper on "Extremist Movements in the Middle East..." in my profile of researchgate.

Jorge Morales Pedraza: No. 2 in your list is humanity's great travesty under a sanctimonious aegis of heroics.

The very profitable manufacture and distribution of arms is morally and ethically wrong. There are more of 'us' than 'them' and we aren't trying hard enough to change the "war culture" to the "peace culture;" we are letting them do it to us!  

Thanks for your comments Dr.Janet Hudgins. Despite the horror of the I and II World War, as well as the Korean War, the Vietnam war, the Balkan wars the Angola war among others, regrettably many countries are still supporting the "culture of war" instead to promote the "culture of diplomacy and peace". What the world need is to produce food to stop the dead of so many people instead of weapons to kill more people.

It is hard to imagine world without terrorism or war. I think our discussion may be useful just in books. In the real world, the mechanisms of terrorisms or wars are out of our control. But I agree with Jorge Morales Pedraza in the power of  improving "culture of diplomacy and peace".

Can we get more covert intelligence personnel to pose as students, worshipers in mosques, act as refugees if need be? 

Please have a look at the following link:

Article Societal Responses to Terrorist Attacks

Try and agree on a single universal definition of terrorism while also accepting regional variations in the definition given historical and cultural background of local terrorist movement.

To curb international terrorism, we must understand the detailed meaning and history of terrorism. Terrorism has a very ancient and long history. The new form of terrorism that we currently know is the result of the ugly face of international politics. For instance, Osama-bin-laden and his terrorist org Al-Qaida.