“That's who I want - or the kind of people that will do that and will pay attention to our history, and know what's what's happened before and know specifically how we can continue to do the good things that we do around the world.”

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Many in the packed auditorium took her words as a coded criticism of Mr Trump, whose foreign policy plans have been condemned as isolationist and weak on detail.

His closest rival Ted Cruz has also made clear that the US has no role in Afghanistan other than fighting terrorism.

In contrast, Mrs Clinton was among those who offered a cover endorsement for Mrs Bush's Afghan book. “For over a decade, Laura Bush has been an ally and advocate for the women of Afghanistan and, in particular, has worked to ensure that the voices of Afghan women are heard,” she wrote.

The two women share a special bond as former first ladies and are of a similar age: both know the struggles of working their way up in a male-dominated world.