WASHINGTON - The next president of Afghanistan will sign a security pact with the United States despite the refusal of outgoing leader Hamid Karzai, Secretary of State John Kerry confidently predicted Wednesday.

“But for one person and his decision we would be on a different track today,” Kerry told a small group of reporters, referring to Karzai who is holding out on signing a bilateral security agreement to govern the presence of any US troops remaining after 2014.

Karzai has refused to endorse the deal, which he hammered out with Kerry last year, saying it should be up to his successor who will be chosen in April presidential elections. “It will be signed by the way,” Kerry insisted.

“Whether it’s signed by him or not we obviously have serious reservations, but all six of the candidates for the presidency of Afghanistan have said that they will sign it.” The Obama administration said its preferred option is to leave behind a residual US force when its combat teams depart Afghanistan after America’s longest war at the end of this year.

But it will not do so without legal protections enshrined in the Bilateral Security Agreement (BSA) agreed between the two governments.

President Barack Obama on Tuesday warned Karzai that he is now planning for a full US troop withdrawal from Afghanistan, invaded by US forces in 2001 to oust the then Taliban militant leadership.

“Specifically, President Obama has asked the Pentagon to ensure that it has adequate plans in place to accomplish an orderly withdrawal by the end of the year should the United States not keep any troops in Afghanistan after 2014,” a White House statement said.

But it added that Obama was reserving the possibility of concluding a BSA with Afghanistan later this year should the new government be willing.

Afghanistan votes on April 5, but a run-off and prolonged horsetrading could mean a government is not seated until August.

In Brussels, NATO defence ministers agreed Thursday the military alliance must now begin planning for a complete withdrawal from Afghanistan this year despite wanting to maintain a troop presence there.

With Afghan President Hamid Karzai refusing to sign a security pact with Washington to allow US troops to stay after 2014, there was no prospect NATO could reach such an accord either, alliance head Anders Fogh Rasmussen said.

“Without the necessary legal framework, there simply cannot be a deployment after 2014,” Rasmussen said.

“So today, we agreed the need to plan for all possible outcomes. Including the possibility that we may not be able to deploy to Afghanistan after 2014, due to the persistent delays we have seen,” he said.

Rasmussen said for NATO, this “is not the outcome we want. It is not the outcome that we think is in the interest of the Afghan people.

“However, it might be the unfortunate outcome if there is no security agreement in due time. This is what is at stake.”

Earlier this week, US President Barack Obama talked by phone to Karzai over his repeated refusal to sign the Bilateral Security Agreement with Washington.

The BSA lays deal the legal basis for a continued US and NATO troop presence in the form of a training mission post-2014.

It is expected to number up to 12,000 troops, mostly American, and is seen as an important guarantee of continued US and NATO support during a difficult transition period.

In 2011, Washington withdrew all its forces from Iraq in a ‘zero option’ when it could not secure an agreement with Baghdad and there are fears a similar outcome in Afghanistan could leave the way clear for the Taliban to return to power.