really? if CIA has defeated USSR which was super power
CIA was absolutely active in Afghanistan (and Pakistan) during the course of
that war. In-fact, both CIA and ISI shook hands for the purpose of transforming the so-called Mujahideen into a potent fighting force to counter Soviet advances in the region. Afghans were not in the position to tackle Soviet Red Army on their own. Conversely, Americans craved for a payback after Vietnam.
why can't they defeat rag-tag militias in Afghanistan after spending trillions of Dollars and 17 years
Afghanistan is a narco-tribal society and in a perpetual state of civil war since the 1960s; its problems are extremely complex accordingly. Rebuilding Afghanistan might not be an attainable goal or so it seems.
Afghanistan does not represent a conventional theater of engagement with visible defenses and advanced infrastructure. A large number of Afghans do not have a productive way of life and are potential recruits for Taliban and ISIS unfortunately. Even though CIA has assassinated thousands of militants in Afghanistan since 2001,
hard-power approach in itself will not be enough to address the problem at hand. Political reforms and employment opportunities are necessary to make difference. US also needs to transition from
conventional model of engagement to
HUMINT model of engagement in Afghanistan, and commit to this cause for long-term. Trump administration seems to get this but a breakthrough will take time, and appropriate public support might not be forthcoming.
Americans invaded Afghanistan to eliminate Al-Qaeda Network and toppled Taliban-led regime in the process (i.e. Operation Enduring Freedom). They also propped up a new regime in Afghanistan which was supposed to manage the affairs of the country. These objectives were clearly defined, and accomplished. Now, it is up to Afghans to embrace the new setup and move past their differences. Scores have embraced it so far (Gulbuddin Hekmatyar being the most recent case) but the entire country is not onboard.
The resurgent Taliban is firmly entrenched in the local environment but an
elusive opponent - not a professional standing army with visible base of operations and advanced support structures to rely upon. Front-lines are also murky, if any. They specialize in hit-and-run attack strategies and do not pick fights with Americans unnecessarily. When a contingent of US Army is dispatched into a Taliban-dominated region in order to clear it, Taliban does not hold ground and rather melts away; this is why
conventional model of engagement will not work. US is engaged in a war of attrition with the Taliban since 2003 but the latter force is never short on recruits.
Interestingly, Taliban-based sources have conveyed to Americans that they will not repeat mistakes of Mullah Omar as in not allow any foreign entity to utilize Afghanistan for its nefarious ends but they demand complete American withdrawal from Afghanistan in return. Taliban-based sources invited an American senator Ron Paul for talks in Qatar, not long ago. FYI:
https://www.theguardian.com/world/2...sh-letter-calling-us-start-afghan-peace-talks
Last, US is not looking forward to exterminate Afghanistan
itself, which it can easily do. There should not be any doubt about American might and power projection capabilities but exterminating an entire country would be viewed as barbaric per modern rules of engagement.
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Total cost of 'War in Afghanistan' is 1.07 trillion USD in a span of 17 years, and much of this cost is logistics-related. The logistics chain stretch back to the US mainland which is 11000+ KM away.