Defense Secretary Chuck Hagel will visit US troops in Afghanistan on Sunday after appealing to Kabul to sign a long-delayed security accord allowing NATO forces to stay in the country after 2014.
Hagel will travel outside the Afghan capital to greet American troops in the field a day after tensions between Washington and Afghan President Hamid Karzai over the stalled security pact were on full public display.
Meetings with the often mercurial Karzai have been customary over the years for Pentagon chiefs but Hagel said Saturday after his arrival that he had no plans to meet the Afghan president during his weekend visit.
As President Barack Obama's top national security adviser, Susan Rice, and top diplomat, John Kerry, had already had frank discussions with Karzai urging him to sign the security agreement, Hagel said there was no point in him merely repeating the US position.
"There's not much I can add in a meeting with President Karzai to what's already been said," he said.
Hagel did meet the Afghan defence minister, who assured him the security agreement would be signed in "a timely manner".
Karzai was scheduled to travel to Tehran on Sunday for talks with Iran, officials said.
The Afghan president initially endorsed the Bilateral Security Agreement (BSA), but has since refused to sign and issued fresh demands.
The security agreement sets the legal conditions to permit US and other forces to operate in the country beyond 2014.
But without a signed deal, countries ready to send troops to a post-2014 training mission cannot make budget plans or secure political approval, Hagel said.
Karzai has said the signature should take place after elections in April, but Hagel said that could push the timeline into mid-2014, as the polls are expected to result in a run-off vote.
Eventually there will be "a cut-off point" to cancel a post-2014 mission, he said, adding that he was "not prepared to give a date on that."
He said a meeting of NATO defence ministers in February would be crucial for military planners and governments "and some answers are going to be required at that NATO ministerial".
However, the Pentagon chief said it would not be productive for the US government to pile pressure on Karzai, and instead the sentiments of the Afghan population were what really mattered.
"I don't think pressure coming from the United States or more pressure is going to be helpful in persuading President Karzai to sign a Bilateral Security Agreement," he said.
Through a loya jirga assembly convened by Karzai, the Afghan people had spoken "rather plainly and clearly and dramatically" in favour of the agreement, he said.
Almost the entire NATO-led force of more than 70,000 is scheduled to pull out by the end of next year.
Under a proposed post-2014 mission, roughly 12,000 troops -- mostly American -- would remain in the country to train Afghans and counter Al-Qaeda-linked militants.