After a lengthy negotiation that lasted nearly a year and contained a number of near breakdowns, Afghanistan and the United States agreed in principle to an agreement that would allow NATO forces to remain in the South Asian country after their mandate expires in 2014.

The deal, referred to as the Security and Defense Cooperation Agreement, is an ambitious document that attempts to lay down the rules and regulations that would govern any future foreign troop presence in the country. It is one that has long topped the agenda of Afghanistan’s president, Hamid Karzai.

Although the two countries have managed to strike a commonality on what the agreement says, the wording could change considerably over the next several weeks, depending on whether the Afghan tribal assembly and parliament chose to amend it.

For the remainder of the week, Karzai will devote significant time and energy to a loya jirga meeting to advocate ratification of the agreement. On its first day, he delivered a lengthy speech in support of a continued foreign military presence, albeit with some caveats on when exactly the document ought to be signed. The United States would like a final agreement in place before the end of the year; Karzai would rather wait until after next year’s presidential election.

The Afghan Foreign Ministry nevertheless posted the security agreement on its website Wednesday night. Whether or not this is the official version is unknown but it outlines a framework for future Afghan-American defense relations. It also strikes a balance in order to take into consideration some of the principles that both countries lobbied for over the previous twelve months.

American soldiers, for instance, would not be permitted to engage in combat without permission from Afghan authorities. Afghan troops “are responsible for securing the people and territory of Afghanistan,” the document reads, and the primary responsibility of foreign personnel is to provide advice and assistance on everything from force preparedness to logistical efficiency and intelligence collection.

At the same time, the Afghans appear to have given the Americans room to conduct unilateral counterterrorism operations against Al Qaeda and other terrorist groups — a key condition for the United States.

Karzai was able to cobble together a key concession in return. President Barack Obama sent a personal letter to his Afghan counterpart’s office reaffirming that American forces would take every effort to respect the sanctity of Afghans in their homes.

“As this new agreement states,” Obama wrote (PDF), “American forces shall not enter Afghan homes for the purposes of military operations, except under extraordinary circumstances involving urgent risk to life and limb of American nationals.”

Obama’s personal assurance is one Karzai can show off to the tribal council, perhaps increasing the likelihood that it accepts the security agreement.

A bone of contention throughout the negotiating process was whether American personnel would be vulnerable to Afghan law in the event of a crime. The Obama Administration threatened that unless soldiers were given immunity, all would be withdrawn in 2014. Despite a number of high-profile cases where civilian casualties were caused by foreign troops, and despite vocal opposition from conservative Afghan politicians that they should be accountable to the local criminal justice system, Karzai agreed to cede legal authority. While this was a difficult pill to swallow politically, Karzai recognized that sticking to his demand would guarantee that Western forces pulled out altogether — which would jeopardize not only the security of Afghanistan but that of his regime as well.

Diplomacy with Karzai has always been difficult. Before the bilateral security pact was agreed upon, negotiators spent two years determining the scale and scope of a deal that would determine the broader bilateral relationship between the two countries. That process, like the current one, ran into considerable roadblocks that imperiled the very signing of an agreement, such as Afghanistan’s demand that foreign troops stop all night raids and that detainees in American facilities be transferred to Afghan control.

Although a deal is now done, success depends on whether a council of some 2,500 Afghan elders approves it and whether the Afghan parliament will ratify it. Only then can Karzai sign it into law.

For now, though, a negotiation that produced major friction between the two countries is nearing its end.