Group elders could also be the lynch pin to resolving the debate over sovereignty issues that has stymied U.S.-Afghan negotiations on a postwar deal.
"If it doesn't suit us and if it doesn't suit them then, naturally we will go separate ways," he told the BBC on Monday.
"If this agreement does not provide Afghanistan peace and security, the Afghans will not want it," the Afghan leader said.
U.S-Afghanistan negotiations for a postwar American presence after the White House-mandated withdrawal in 2014 have been fraught with disagreements and frayed relations between the two countries since they began in 2011.
Most recently, Washington's plan to have U.S. special operations forces and American intelligence operatives conduct missions against the Taliban and al Qaeda elements inside Afghanistan after the White House's 2014 withdrawal deadline is "a deal breaker," according Aimal Faizi, spokesman for Afghan President Hamid Karzai.
Despite those disagreements, there has been some progress in the talks.
Afghan and American diplomats have begin coalescing around a final number of U.S. forces to remain in country. The total postwar force will likely be about 10,000 soldiers, according to Afghan Foreign Minister Zalmai Rassoul.
That figure matches rough troop estimates circulating on Capitol Hill.
But a former top Afghan government official warned that if Kabul and Washington cannot agree on the rest of the postwar security deal, known inside the Pentagon as a bilateral security agreement (BSA), the country will fall apart.
"All that has been invested in blood and treasure will go with the wind, and the destiny of this country will go back to square one," Afghanistan's former defense minister Gen. Abdul Rahim Wardak told the AP.
The agreement will lay the groundwork for a postwar American force and grant legal immunity for U.S. troops in that force.
Lack of immunity for U.S. troops was a crucial factor in the failed attempt to set up a postwar security deal in Iraq, and it set the stage for the recent wave of sectarian violence against Iraqi forces and civilians in the country.
There are roughly 55,000 U.S. troops in Afghanistan, but most are expected to go back to the United States over the coming months.
The final American units will return stateside after the April 2014 presidential election, marking the end of the American war in Afghanistan.