Pakistan's ace in poker match with US: Afghan air routes

As bad as President Donald Trump describes US-Pakistani ties today, they can get far worse.

Over 16 years that included hundreds of deadly US drone strikes, Osama bin laden's killing on Pakistani soil and accusations Pakistan helps insurgents that kill Americans, the reluctant allies never reached one point of no return: Pakistan closing the air routes to Afghanistan.

It's an action that could all but cripple the US-backed military fight against the Taliban. It could also be tantamount to Pakistan going to war with the United States.

Even if such a step is seen as unlikely by most officials and observers, Pakistan's ability to shape the destiny of America's longest war is a reminder of how much leverage the country maintains at a time Trump is suspending hundreds of millions of dollars in military assistance.

"There's some suggestion that we have all of the cards in our hands," said Richard Olson, a former US ambassador to Pakistan. "But we don't. The leverage is strong on the Pakistan side as well and arguably stronger than our side."

Trump's re-commitment of US forces to the fight in Afghanistan makes the stakes high for his administration. The top US diplomat for South Asia, Alice Wells, made a low-key visit to Islamabad this week, suggesting both sides want to prevent a breach in ties.

Pakistan's cooperation is needed not only to reduce violence in its northern neighbor. It's also critical to any hope of a political settlement with the Afghan Taliban after decades of conflict.

Defence Secretary Jim Mattis has said the US doesn't expect Pakistan to cut off supply routes. Even so, the US is seeking out alternatives, a senior administration official said, without elaborating on what those routes might be.

The Pentagon wouldn't discuss the issue, citing operational security, other than to say military planners develop "multiple supply chain contingencies" to sustain their mission.

The administration official, who wasn't authorised to comment by name and demanded anonymity, said it would be "very difficult" but not impossible for the US to get military equipment into Afghanistan if the Pakistan route is shut down.

Restrictions limit what types of supplies can flow through the Northern Distribution Network in Central Asia, set up during the Obama administration amid concerns about relying solely on Pakistan.