With the passage of resolution by the Arabs and te continuing atrocities against civilians in Syria it is possible for NATO to use Turkey to push a war.
In about 6-12 hours time, Turkish forces can move into Syria to provide a 'humanitarian corridor'. This will be interpreted as an unmitigated act of war. Iran will be called upon by Syria to join them to strike Turkey. They will do so. At that time, NATO will unleash contingency 313. Under Contingency 313, a full scale invasion of Syria and Iran are to be carried out, with troops in Afghanistan pressing themselves on the border of Pakistan in case they decide to join in.
The reason troops will stay predominantly on the border with Pakistan is because the Pakistani army is significantly larger than the Iranian army, and is the bigger threat. About 40% of the troops in Afghanistan have been moved to the west on the border with Iran. They will hold the line until reinforcements arrive and while air operations are carried out.
This is a serious possibility. Things can hit up pretty soon. Iran getting involved will mean the NATO will target its nuke centers.