Losing. Or winning.
First, if an insurgent perceives himself to be “winning,” he will not negotiate unless it is to freeze the government in place while the insurgent prepares himself for the final push to topple the government. This has happened numerous times throughout history, with insurgents negotiating a change in military tactics or limiting the use of weapons. This then gives the insurgent time and space in which to solidify his gains and reach the tipping point on the verge of victory. In the case of foreign assistance to the host nation government, a key negotiating point for the insurgents will be the limiting or removal of foreign forces. A government teetering on collapse is more amenable to such negotiations. A foreign assistance force is more amenable to negotiate their own withdrawal in such cases as well. Either way, the objective of the ascendant insurgent is to cause the government to expose itself to easier military conquest. The idea is that if you break your word, but you win, you get to write the history. Oddly, numerous governments have fallen for the ploy over time.
What about “losing?” Either the insurgent has to be visibly losing or he has to perceive that he is losing. Does it have to be the threat of imminent defeat? Not necessarily. That depends on many factors.
A favorite (and effective) insurgent propaganda catchphrase in Afghanistan is, “The Americans have the watches, but we have the time.” Data shows that the longer an insurgency drags on, the likelihood of insurgent success actually decreases. So we have competing ideas. One is based on data, and it’s only an incremental change in counterinsurgent success. But it is real, based on “resolved” insurgencies. The other is a catchy phrase leveraged with our own popular history. We are seen, especially in the region, as being fickle friends. In a nation with a strong oral history and a love for analogy, shaping popular perceptions of our history through ready memes is fairly easy. Afghans often perceive that America lost interest in them at a critical time, ultimately resulting in the rise of the Taliban. HiG leader Gulbuddin Hekmatyar hates the United States for failing to support his drive to take over Afghanistan following the withdrawal of the Soviets, having his own tale of American abandonment. Afghan insurgents have their own reasons for either beginning to seek a settlement or not, but if they begin to feel as if they are running out of time, the mental door to compromise begins to open.
Mullah Omar is said to be adamantly opposed to negotiations. While Omar would be a key figure to negotiate a cessation of hostilities and a return to civil life for the Quetta Shura Taliban, a failure on his part to participate would possibly cause fractures in the QST. Sub-commanders who view the situation differently may break with the Taliban to negotiate on their own. Some of this has apparently happened.
Most likely it is not due to one issue, but a combination of effects on the insurgency. Fatigue, and the fatigue of the population, may have something to do with the higher failure rate amongst insurgencies of longer duration. Real progress by the government on the issues upon which the insurgents rely for leverage may also play a role. Difficulty in mounting attacks due to improved security and lower recruitment will also play a role.
The HiG were actually a more violent spin-off of the Hizbi islami Kulis (HiK), a political party. Many “former” HiG participate in GIRoA. While coalition members view them with considerable caution, they are participating in the process. They often maintain contacts with their former comrades in arms. Gulbuddin will likely never participate himself, but is not beyond the realm of possibility. Again, fractures and defections may come into play and apparently already have. Given the ceding of areas of the RC East by the coalition in the past year and a half, the HiG are not likely feeling disadvantaged.
The Haqqani network, with the closest ties to al Qaeda, is another question.
Finally reconciliation programs that provide honorable reintegration for former insurgents, often combined with a higher mortality rate associated with participation in the insurgency, provide a powerful inducement to cease fighting. Mistreatment of insurgents by the host nation government does not provide a similar benefit.
In the end, if the insurgency feels that they are “winning,” they will not negotiate except for deceptive reasons. If they perceive themselves to be “losing,” they will begin to have difficulty with more than one factor of the overall insurgency and will become more likely to negotiate. The participation of the leadership is very helpful, but in the end the insurgency consists of many individuals who must decide for themselves when they are no longer willing to kill.