On every level, no matter how you cut it, ISIS is a product of U.S. government's twisted and decrepit foreign policy.
Now all of this may seem contradictory to you as you watch the drums of war against ISIS begin to beat louder and the air strikes against them are gradually widened http://www.wjla.com/articles/2014/08/president-obama-considers-possible-...). Why would the U.S. help a terrorist organization get established, only to attack them later?
Well why did the CIA put Saddam Hussein in power in 1963?, Why did the U.S. government back Saddam in 1980 when he launched a war of aggression against Iran, even though they knew that he was using chemical weapons? Why did the U.S. fund and arm Islamic extremists in Afghanistan against the Soviets?
There's a pattern here if you look closely. This is a tried and true geopolitical strategy.
Step 1: Build up a dictator or extremist group which can then be used to wage proxy wars against opponents. During this stage any crimes committed by these proxies are swept under the rug. [Problem]
Step 2: When these nasty characters have outlived their usefulness, that's when it's time to pull out all that dirt from under the rug and start publicizing it 24/7. This obviously works best when the public has no idea how these bad guys came to power.[Reaction]
Step 3: Finally, when the public practically begging for the government to do something, a solution is proposed. Usually the solution involves military intervention, the loss of certain liberties, or both. [Solution]
ISIS is extremely useful. They have essentially done Washington dirty work by weakening Assad. In 2014, while the news cycle has focused almost exclusively on Ukraine and Russia, ISIS made major headway in Syria, and as of August they already controlled 35% of the country.
Since ISIS largely based in Syria, this gives the U.S. a pretext to move into Syria. Sooner or later the U.S. will extend the airstrikes into Assad's backyard, and when they do U.S. officials are already making it clear that both ISIS and the Syrian government will be targeted. That, after all, is the whole point. Washington may allow ISIS to capture a bit more territory first, but the writing is on the wall, and has been for some time now.
The Obama administration has repeatedly insisted that this will never lead to boots on the ground, however, the truth of the matter is that anyone who understands anything about military tactics knows full well that ISIS cannot be defeated by airstrikes alone. In response to airstrikes ISIS will merely disperse and conceal their forces. ISIS isn't an established state power which can be destroyed by knocking out key government buildings and infrastructure. These are guerrilla fighters who cut their teeth in urban warfare.
To significantly weaken them, the war will have to involve ground troops, but even this is a lost cause. U.S. troops could certainly route ISIS in street to street battles for some time, and they might even succeed in fully occupying Syria and Iraq for a number of years, but eventually they will have to leave, and when they do, it should be obvious what will come next.
The puppets that the U.S. government has installed in the various countries that they have brought down in recent years have without exception proven to be utterly incompetent and corrupt. No one that Washington places in power will be capable of maintaining stability in Syria. Period.
Right now, Assad is the last bastion of stability in the region. He is the last chance they have for a moderate non-sectarian government and he is the only hope of anything even remotely resembling democracy for the foreseeable future. If Assad falls, Islamic extremist will take the helm, they will impose shari'ah law, and they will do everything in their power to continue spreading their ideology as far and wide as they can.
If the world truly wants to stop ISIS, there is only one way to do it:
1. First and foremost, the U.S. government and its allies must be heavily pressured to cut all support to the rebels who are attempting to topple Assad. Even if these rebels that the U.S. is arming and funding were moderate, and they're not, the fact that they are forcing Assad to fight a war on multiple fronts, only strengthens ISIS. This is lunacy.
2. The Syrian government should be provided with financial support, equipment, training and intelligence to enable them to turn the tide against ISIS. This is their territory, they should be the ones to reclaim it.
Now obviously this support isn't going to come from the U.S. or any NATO country, but there are a number of nations who have a strategic interest in preventing another regime change and chaotic aftermath. If these countries respond promptly, as in right now, they could preempt a U.S. intervention, and as long this support does not include the presence of foreign troops, doing so will greatly reduce the likelihood of a major confrontation down the road.
3. The U.S. government and its allies should should be aggressively condemned for their failed regime change policies and the individuals behind these decisions should be charged for war crimes. This would have to be done on an nation by nation level since the U.N. has done nothing but enable NATO aggression. While this may not immediately result in these criminals being arrested, it would send a message. This can be done. Malaysia has already proven this by convicting the Bush administration of war crimes in abstentia.