The disarming of ethnic Albanian guerrillas, no less essential to peace, will not be easy.
If ethnic Albanian guerrillas score some victories, they may hope to persuade supporters that independence can be won without a peace deal.
The ethnic Albanian guerrillas and their political allies have largely endorsed the plan, which was presented to both sides in the conflict as essentially non-negotiable.
The ethnic Albanian guerrillas have killed Serbian police and taken soldiers hostage.
More than 900 people have been reported killed in the fighting this year, most of them ethnic Albanian guerrillas and civilians.
Their job will be to collect weapons handed over voluntarily by the ethnic Albanian guerrillas who have been fighting the government for six months.
Any effort at this point to send arms to ethnic Albanian guerrillas, an idea gaining support in Congress, would be unwise.
In the peace agreement, 3,000 ethnic Albanian guerrillas laid down their weapons, and several are now members of the government.
Meanwhile the ethnic Albanian guerrillas rearmed and peace negotiations went nowhere.
Former ethnic Albanian guerrillas are now members of a coalition government with a center left Macedonian party.