"Is America loosing its grip on being the global hegemon
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Can it continue to lead by example or will it have to eventually call in the Cavalry?
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"Eventually" call in the cavalry ? ? ?.
The US military has been at war almost none stop since WW2 to maintain it's grip. Or war thru proxy (contra's), and CIA assassinations, torture and coup's and CIA sponsored military dictatorships, Chile, Argentina, Egypt a few examples.
Now taking aim at Russia or/and China. The planning, preparations and war propaganda are already well underway.