What's behind the Afghanistan-Pakistan border flare-up?

There's tension at the border crossing between Afghanistan and Pakistan as forces exchanged gunfires. So, what's behind this recent flare-up? 

Join host Tom McRae.

Guests:

Faiz Zaland - Professor of political science at Kabul University.

Orzala Nemat - Director of Development Research Group.

Ayaz Wazir - Pakistan's former ambassador to Afghanistan.