Security tightens as Afghan presidential election looms

There is a huge security operation in Afghanistan as presidential candidates prepare for Saturday's vote. The new president will succeed Hamid Karzai, who has been in power since the 2001 fall of the Taliban but is constitutionally barred from seeking a third consecutive term. It should be the first time that power is democratically transferred.

Background:

Huge security as Afghan presidential election looms [BBC]

What if the Afghan elections actually work? [CNN]

Afghanistan election: domestic and international spoilers [Al Jazeera]