ISLAMABAD – As bad as American President Donald Trump describesUS-Pakistani ties today, they can get far worse.

Over 16 years that included hundreds of deadly US drone strikes — Osama binLaden’s killing on Pakistani soil and accusations Pakistan helps insurgentsthat kill Americans — the reluctant allies never reached one point of noreturn: Pakistan closing the air routes to Afghanistan.

It’s an action that could all but cripple the US-backed military fightagainst the Taliban. It could also be tantamount to Pakistan going to warwith 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 areminder of how much leverage the country maintains at a time Trump issuspending hundreds of millions of dollarslink>inmilitary assistance.

‘Don’t have all the cards’

“There’s some suggestion that we have all of the cards in our hands,” saidRichard Olson, a former US ambassador to Pakistan. “But we don’t. Theleverage is strong on the Pakistan side as well and arguably stronger thanour side.”

Trump’s re-commitment of US forces to the fight in Afghanistan makes thestakes high for his administration. The top US diplomat for South Asia,Alice Wells, made a low-key visit to Islamabad this week, suggesting bothsides want to prevent a breach in ties. Pakistan’s cooperation is needednot only to reduce violence in its northern neighbour. It’s also criticalto any hope of a political settlement with the Afghan Taliban after decadesof conflict.

US defence secretary Jim Mattis has said the US doesn’t expect Pakistan tocut off supply routes. Even so, the US is seeking out alternatives, asenior administration official said, without elaborating on what thoseroutes might be. The Pentagon wouldn’t discuss the issue, citingoperational security, other than to say military planners develop “multiplesupply chain contingencies” to sustain their mission.

The administration official, who wasn’t authorised to comment by name anddemanded anonymity, said it would be “very difficult” but not impossiblefor the US to get military equipment into Afghanistan if the Pakistan routeis shut down. Restrictions limit what types of supplies can flow throughthe Northern Distribution Network in Central Asia, set up during the Obamaadministration amid concerns about relying solely on Pakistan.

When Pakistan cut access

Pakistan has cut overland access before. When a US airstrike killed 24Pakistani soldiers at the Afghan-Pakistan frontier in late 2011, monthsafter the US commando raid that killed bin Laden, Pakistan blocked bordercrossings into Afghanistan.

The decision sunk US-Pakistani relations to a post-9/11 low point. Supplytrucks that trundle across the desert into Afghanistan’s southern Kandaharprovince or into Nangarhar via the mountainous Khyber Pass ground to ahalt. Hundreds of containers shipped from the US or the Gulf were leftstranded in the Pakistani port of Karachi until mid-2012.

For the US, truck and rail costs inflated by about 50%, said David Sedney,a former Pentagon official who organised the alternative northern routes.He said deliveries by air cost three times as much or more.

But the saga, resolved through a US apology, also exposed the limits ofPakistan’s leverage, Sedney said. Pakistan’s own economy was hurt, notablythe military-dominated trucking industry. And the Afghan war effort, whichwas then supporting more than 70,000 US troops, compared with around 16,000now, endured.

That was perhaps the result of Pakistan never closing the air corridor intoAfghanistan, which US pilots call “the boulevard”. It’s essential forferrying ammunition and weapons for US and Afghan forces, and waging war.US intelligence flights and combat missions use it when taking off from USbases in the Persian Gulf or from aircraft carriers in the Indian Ocean.

Since closing Pakistan’s airspace would hinder America’s ability to defendits forces in Afghanistan, Olson, the former ambassador, said the US mightregard such action as a “casus belli,” or grounds for war. Other former USofficials echoed that assessment.

“From what I can tell we don’t actually have any serious alternative,” saidDaniel Markey, a South Asia expert at the John Hopkins School of AdvancedInternational Studies.

Sedney said the Northern Distribution Network, which fell out of use aftermost US forces were withdrawn from Afghanistan by late 2014, could berestored with astute US diplomacy. Nations such as Uzbekistan, Kyrgyzstan,Tajikistan and Kazakhstan all have been used before for transporting mostlynon-lethal supplies. Poor US relations with Russia could make the tasktrickier, however. Moscow wields significant influence over these formerSoviet states.

What next

Pakistan is weighing options carefully. The suspension of around $1.2billion in assistance and Trump’s accusations of Pakistani “lies and deceit”link>forallowing Taliban havens have stirred anger and demands from oppositionparty leader Imran Khan for both land and air links to be cut.

Pakistan’s ambassador in Washington, Aizaz Chaudhry, indicated such stepsweren’t imminent, urging greater US cooperation on counterterrorism. But hewarned that further downward spiraling in US-Pakistani ties could create asituation in which “everything will be on table”.

Chaudhry cited Pakistan’s long-standing complaints that its efforts havebeen unappreciated, claiming that most leaders of the Haqqani network —which the US hopes to eradicate — have fled to Afghanistan. Critics sayPakistan’s military only targets insurgents threatening Pakistan itself.

“The problem is we have a porous open border and it’s like a revolvingdoor,” said Chaudhry. “These elements tend to come back, and travel backand forth, but there is no organised presence or safe havens insidePakistan.”

Republicans and Democrats in America aren’t sold. Lawmakers have urgedtargeted financial sanctions against Pakistani intelligence officialslinked to militants, and for Pakistan to lose its “non-NATO ally” statusthat offers preferential access to US military technology. ZalmayKhalilzad, a former US ambassador in Kabul, is among hawks advocatingPakistan be declared a state sponsor of terrorism, unless it cooperates.

But others who’ve worked with the Pakistanis fear coercion could backfireat a time they’re hedging their bets, unsure America will win inAfghanistan.

A tacit Pakistani alliance with the Taliban will appear “more important tothem than ever as we turn once again from an ally into an adversary,” saidRyan Crocker, who was US ambassador in Pakistan and Afghanistan. AGENCIES