President Barack Obama has again provoked criticism of how he talked about terrorist acts in the immediate wake of the brutal execution of Jordanian air force pilot Moaz al-Kasasbeh by the sell-proclaimed Islamic State (IS). This follows earlier criticism comcerning the administration's failure to call the Afghan Taliban a terrorist organization. While there is some truth in the charges that Obama is indulging in political correctness or showing a reluctance to admit the extent of terrorism, there is also truth in the statement of White House spokesman Eric Schultz that the Taliban is an "armed insurgency" that uses terror tactics rather than being an actual terrorist group.

Terrorism is the lowest form of war. It doesn't take much of an organization or force structure to plant bombs or assassinate foes. It is what adversaries do when they do not have the strength to do anything more, such as actually overthrow a regime or conquer territory. An insurgency is what a terrorist group can grow into if it is not crushed in its infancy. Insurgent forces like the Taliban in Afghanistan, Islamic State in Syria and Iraq, Hamas in Gaza, and Boko Haram in Nigeria have regular troops in the field and have taken territory. Before 9/11, the Taliban controlled most of Afghanistan, including the capital Kabul. Indeed, it was seeking international recognition as the legitimate government.

The Taliban made the strategic error of sheltering al-Qaeda even after the 9/11 attacks, thus provoking a counterattack from the United States and a multilateral intervention by NATO that drove the Taliban out of Afghanistan. Unfortunately, the Taliban were left with sanctuaries in Pakistan it could use to rebuild an army. It still uses terror tactics in places like Kabul which are beyond the reach of its troops, but its aim is still to conquer the country. It is thus an insurgency that is capable of holding territory, not just a terrorist group.

Islamic State has also graduated into an insurgency with control of large sections of both Syria and Iraq, including oil fields and a large population to plunder and conscript. It is an army. The same holds true for Boko Haram, which has the strength to set up territorial "no go" zones where it rules and invokes Sharia law.

The evolution and growth of violent movements requires a change in strategy from what the U.S. has been using in the so-called "war on terror." Drone strikes and special operations can disrupt and knock down terrorist groups, but they are not capable of defeating insurgent armies in the field. Even heavier air strikes by conventional warplanes will not liberate conquered lands. It will take ground troops to do that. In the end, there must be an armed force that can kick in the door of the enemy headquarters, tear down its flag and hoist a new banner in its place -- just as the insurgents did when they were on the offensive.

President Obama does not want those troops to be American, but has yet to find enough others to take up the sword. And where there are those willing to link their cause with ours in combat, the administration has been reluctant to provide weapons and less than competent in giving other forms of support or training. Insurgencies grow on the basis of success. Recruits are attracted by winners. Mao Zedong in his writings on guerrilla warfare in China laid out the step-by-step process of creating out of nothing an army that could defeat the military of even a major government. The lesson should be learned in reverse as well; that the key to defense is to destroy enemies early, while they are still small and weak.

There are other insurgent armies that will be even more difficult to defeat because they do receive heavy support from governments who see them as their spearheads. Hizb’allah is backed by Iran, the rebels in eastern Ukraine by Russia, and the Taliban is still backed by powerful factions in Pakistan.

Counterinsurgency is not hopeless. The long-running insurgency by the Tamil Tigers in Sri Lanka was defeated by government forces that were able to conduct a ruthless campaign with substantial material support from China. Beijing expects to be compensated by being allowed to use Sri Lankan ports as its navy expands its operations into the Indian Ocean. French armed and trained troops from Cameroon and Chad are starting to move against Boko Haram. And Iran and Hizb’allah have kept the Assad regime alive in Syria. The Obama administration, however, has no apparent strategy for dealing with insurgent armies beyond refining its use of terminology.

The recent announcement that the U.S. may start to honor the pleas from Ukraine for modern weapons to fight the Russian-backed rebels is a hopeful sign. Aid to the Kurds in Iraq finally drove back IS, though the Kurds are not strong enough to advance any further. But if new aid still falls within the "too little, too late" approach the administration has taken so far (prime example being Syria), it will not bring decisive victory over any foes on any front. Someone has to put boots on the ground, in large enough numbers and with sufficient firepower to drive the enemy against the wall and then finish them off. That is certainly what the insurgents aim to do to our friends and allies unless stopped.

The "war against terror" is not over and must continue to be waged, but it must be superseded by the greater demands of the war against enemy armies on the march of conquest.