CARTAGENA, Colombia _ After four years of tense negotiations, leaders from across the Western Hemisphere gathered here Monday with leftist Colombian guerrilla commanders and President Juan Manuel Santos to sign a landmark peace accord that will officially end five decades of civil war.
Now comes the hard part.
By the only official accounting, 267,162 people were killed in the hemisphere's longest war. During the 1990s, Supreme Court justices and politicians were routinely assassinated and Colombia teetered on becoming a failed narco-state.
"Today we have a reason for hope: There is one less war on the planet," Santos said before the signing ceremony. "And that is the war in Colombia."
Secretary of State John F. Kerry, who led the U.S. delegation, hailed the peace process as a success for U.S. diplomacy.
"It is time to put the past behind us and start to write a new future for Colombia," Kerry told reporters before the ceremony.
Bernard Aronson, a special U.S. envoy to the peace talks, noted how arduous the negotiations had been. "This is a good peace," he said. "There were no winners and no losers. Everyone won peace."
President Barack Obama has lauded the accord as one of his administration's most important foreign policy achievements. Along with the U.S. rapprochement with Cuba, it marks the end of the last Cold War-era conflict in the Americas.
Much of the credit, U.S. officials say, goes to the U.S.-financed Plan Colombia, which poured billions of dollars into the country to help the government fight the guerrillas.
But critics say Plan Colombia, which is being used as a model for Central America and elsewhere, had serious flaws.
Even supporters of the strategy of full-bore military support for the Colombian army say human rights should have been addressed earlier.
The war gave rise to egregious abuses by the army, including extrajudicial assassinations and the rise of murderous right-wing paramilitary death squads. The leftist guerrillas also committed atrocities, including sexual enslavement of women and kidnappings of civilians.
In recent years, Plan Colombia evolved into Paz (Peace) Colombia and began to shift money to nonmilitary sectors, such as justice institutions and development.
Although aid still tilts toward Colombia's army, the Obama administration aims to spend $450 million helping the Colombian government extend basic services into long-neglected rural areas, fighting drug-trafficking and other civilian needs.
Distribution of U.S. aid is only one of the hurdles as the accord goes into effect. Sponsors of the peace process are bracing for multiple challenges.
Under the agreement, an estimated 7,000 fighters from the Revolutionary Armed Forces of Colombia, or FARC, will lay down their weapons and rejoin civilian life, along with 17,000 noncombatant followers.
"Many of these were taken (by the FARC) as children and they know no other life," said Marcela Escobari, an official with the Latin America bureau of the U.S. Agency for International Development. "If they are not given alternatives, they will turn to some sort of illicit activity. Reinsertion will be very complicated."
Kerry seemed to leave the door open Monday to removing the FARC from the U.S. list of foreign terrorist organizations. He said the Obama administration would review the designation as the rebels' demobilization and reconciliation became "facts."
The list of potential spoilers is long.
A former Colombian president is leading a campaign to derail the agreement. Dissident guerrillas may refuse to lay down their guns. Some communities where demobilized rebels are to be resettled have balked at the idea.
There are many in Colombia, especially those involved in the super-lucrative drug trade, who would be happy to see the country remain in a state of conflict.
U.S. officials are particularly worried that demobilized guerrillas could be targeted for assassinations to discourage peace, as has happened in other post-conflict societies.
"Spoiling is much faster and easier than making peace," said a senior U.S. official, speaking on condition of anonymity in keeping with Obama administration rules. "It took four years to make peace, and it can be destroyed in four minutes."
The United Nations will be charged with monitoring how the peace deal unfolds, much as it did at the conclusion of the wars in El Salvador and Guatemala in the 1990s.
But the Colombia mission will be more complicated. For starters, the country has more armed factions than existed in other Central American conflicts. It also has a far greater component of criminal activity, primarily in the form of drug traffickers.
In addition to helping to demobilize the rebels, the agreement calls for issuing land titles to peasants and expanding education and other government services into rural areas.
Santos will put the deal to a popular vote on Sunday. The referendum is not legally binding but he has said he wants all Colombians to invest in peace.
"Vote yes! Let's make peace now," urge government billboards here in the colonial gem of Cartagena on the Caribbean coast.
Many in Colombia view the accord with a mix of hope and skepticism. Especially for those who suffered the most, there is dismay that many of the fighters will be given immunity from prosecution.
"Some people want justice," said Jose Samuel Garcia, a priest in San Vicente del Caguan, a town in a FARC stronghold in southern Colombia. "Not everybody is capable of forgiveness."
That seemed clear early Monday when Kerry met with former combatants and land mine victims at a vocational school where former guerrillas are learning to become hairdressers and carpenters.
"This, what is happening today, is very positive," a 23-year-old former guerrilla who gave his name as Jonathan told Kerry. "But it is not going to end the war." He predicted many FARC members will simply "change their armbands" and join other armed groups.
