The nature of state failure varies from place to place, sometimes dramatically. Failure and weakness can flow from a nation’s geographical, physical, historical, and political circumstances, such as colonial errors and Cold War policy mistakes. More than structural or institutional weaknesses, human agency is also culpable, usually in a fatal way. Destructive decisions by individual leaders have almost always paved the way to state failure. ~ American historian Robert Rotberg
State-building is a prolonged exercise in establishing the institutions necessary for governance, particularly the military means to secure territory, policing to maintain peace, judicial administration, and tax collection to support governance. Legitimacy in the eyes of the governed is also essential.
Most countries that fall apart do so not with a bang but with a whimper. They fail not in an explosion of war and violence but by being utterly unable to take advantage of their society’s huge potential, condemning their citizens to a lifetime of poverty. This failure is by design. These states collapse because they are ruled by “extractive” economic institutions which are not in place by mistake but on purpose. They’re there for the benefit of elites who gain much from the extraction — whether in the form of valuable minerals, forced labor, or protected monopolies — at the expense of society. Of course, such elites benefit from rigged political institutions too, wielding their power to tilt the system for their benefit. ~ Turkish American economist Daron Acemoglu & English political scientist James Robinson
To put it mildly, constructing a state is problematic; and so, as products of war, tribalism, or an exploitative elite, modern history is littered with failed states.
The heaviest concentration of failed states is in Africa, where the legacy of colonialism did not birth decent governance. Southwestern Asia also has more than its share of failed states, owing to Islam being a factionalized religion fervently followed by hotheads.
As part of its war of terror, the United States invaded Afghanistan in 2001 and Iraq in 2003. Both countries were quickly conquered by the overwhelming military power applied. In both instances, the occupation that followed proved stupid fumbling. As the United States lacks the skill and patience for state-building, both Afghanistan and Iraq became failed states.
Before the US invasion, Iraq had been a dictatorship under Saddam Hussein. Decapitating Iraq’s leadership and dismantling its military led to a failed state, owing to corruption and Islamic warlordism.
Afghanistan had been a monarchy until 1973, when a military coup overthrew it. Political turmoil ensued.
The Soviets invaded in 1979, and malignantly lingered for a decade, unable to overcome local resistance. A political vacuum was left when the Soviets withdrew. Their puppet government was unable to attain legitimacy.
The Afghani mujahedeen who won the war of attrition were warlords, not state builders. Afghanistan became a failed state. The US simply stirred the political rubble for a time with their own prolonged Soviet-style occupation. Afghanistan was a failed state when the US romped in and disintegrated as the US lingered with its useless troops.