If we knew for sure how to stop ISIS, we probably would have already done so. Anything we say about stopping this group is purely speculative.
ISIS is a radical jihadist group of Sunni Muslims. This group aspires to create a country that is ruled by Islam. It also aspires to hold power over all Muslims around the world. This makes it different, for example, from Al-Qaeda which does not seek to hold territory and political power.
Some possible ways to stop ISIS:
- Invade their territory. Since ISIS wants to gain and keep control over a given territory, it should be possible to invade that territory and defeat ISIS militarily.
- Reduce the incentives for people to join ISIS. Many people support ISIS because they dislike the governments that ISIS opposes. For example, ISIS gets much of its legitimacy from its opposition to the Assad government in Syria. Getting Assad out of Syria and replacing him with a popular government would reduce people’s grievances and make them less likely to support ISIS. At the same time, countries could push for less authoritarian governments in other parts of the Muslim world so that there would be fewer Muslims who are angry enough to join or support ISIS.
- Pressure Saudi Arabia to stop spreading Islamism. Saudi Arabia, one of the US’s main allies in the Middle East, funds the spread of a very militant form of Sunni Islam known as Wahhabism. This helps radicalize many Sunnis against both the West and against Shiites.
- Pressure Iran to stop supporting Shiite opposition to Sunni governments. Part of ISIS’s power comes from the idea that there is a struggle between the Sunnis and the Shiites in the Middle East. Iran is a Shiite power and it tries to back Shiites across the region. This helps make Sunni groups like ISIS feel that they are threatened and must fight back.
- Try to cut off the sources of funding for ISIS. We could try to use the international banking and money transfer systems to cut off any money that is going to ISIS. We could impose sanctions on any countries that allow support to flow to ISIS. Reducing the flow of money to ISIS would weaken it.
All of these things are theoretically possible, but they all have major difficulties, which is the main reason why ISIS continues to be strong.