WASHINGTON: Pentagon officials are watching for Pakistan´s next moves afterWashington froze security aid payments to Islamabad, saying it is not doingenough to target Afghan Taliban and Haqqani group bases.

The Trump administration´s decision to withhold hundreds of millions fromits “coalition support funds” has riled Pakistan, with some there callingfor retaliatory measures that might hamper America´s warfighting efforts inneighboring Afghanistan.

Most problematic for America as it wages its 16-year war in Afghanistanwould be if Pakistan suddenly shut its border points into the country,stemming the vital flow of goods, food and gear from the port at Karachi.

Though US officials insisted they´d seen no evidence Islamabad was planningsuch a move, it has happened before.

In 2011, Pakistan closed its border to NATO supplies following a series ofincidents that brought relations between the US and Pakistan to all-timelows.

These incidents included a botched American air raid and the killing ofOsama bin Laden, who was living in the Pakistani city of Abbottabad.

At the time, the US-led forces in Afghanistan endured the closure byrelying on cargo flights and a more costly northern route through Russia,Central Asia and the Caucasus.

Citing security reasons, the Pentagon declined to provide percentages of USsupplies going into Afghanistan through Pakistan, but Afghan securityforces in particular rely on the supply lines through Pakistan, with astream of trucks hauling a plethora of goods into the landlocked country.

While the US favors Pakistan supply routes because of cost, officialsstressed America has built “flexibility and redundancy” into its supplychains.

“As military planners, we develop multiple supply chain contingencies tosustain theater requirements to maintain the train, advise and assistmission to the Afghan National Defense Security Forces,” Lieutenant ColonelKone Faulkner told AFP.

In Pakistan, several figures were quick to call on their government toclose supply lines, including opposition leader Imran Khan.

“The time (has) come to stand firm and give a strong response to the US,”Khan said in a statement.

“We must deny the US (supply route) facilities which we were providing theUS free of charge.”

But Defense Secretary Jim Mattis told Pentagon reporters he had gotten noindication the Pakistanis were going to shut off ground supply lines, orair overflights.

– ´Humongous problem´

“I am not concerned about them,” he said, referring to the supply lines.

Mattis said the US continues to work with Pakistan and would restoresecurity payments “if we see decisive movements against the terrorists whoare as much of a threat against Pakistan as they are against us.”

For Christine Fair, a South Asia expert at Georgetown University, this partof the problem is key.

The Trump administration must clearly lay out what it expects from Pakistanand what additional punitive steps would be taken if it shuts down thesupply lines, she said.

She was particularly concerned about the possibility of Pakistan closingits air space to America, meaning efforts to fly air cargo into Afghanistancould get much more difficult.

Pakistan “could within its rights… say you will not use our air space,”she said. “That would be a humungous problem.”

Unlike in 2011, the US no longer has an air base in Kyrgyzstan, which hadbeen the main transit point for American military personnel and cargo inand out of Afghanistan but was abandoned amid a price row in 2014 with theObama administration.

Additionally, Washington´s fraught relations with Russia could make flyingover Central Asian states less reliable, with Moscow able to exertinfluence on its smaller neighbors.

After more than a decade of simmering US anger at Islamabad´s links withthe Afghan Taliban and the Haqqani network — a Taliban affiliate — theTrump administration is trying to draw a line in the sand.

Fair said almost all US deaths from the Taliban in Afghanistan can beattributed to the Pakistanis.

“They literally take our money with one hand and they give it to theTaliban with the other,” she said.

“You cannot fight a war and win when the country you are dependent upon forlogistical supplies is undermining your efforts there.”

A US defense official told AFP that the military already has plenty ofoptions to keep its troops well supplied, and could fill gaps by charteringcommercial air delivery planes.

“The question is, if it were to happen, how long would it last?” theofficial said.

Weeks or months would probably be “something that we could deal withthrough temporary solutions and wouldn´t matter so terribly much.”

But a longer-term embargo would require the US to find more practicalsolutions, and these would come with a high price tag, the official added.