The government's objective is to pacify violent regions and put Colombia on a path to peace by blunting the appeal of a guerrilla group that uses the banner of land reform to justify its struggle.
"This is as critical a stage as you could imagine - what we do with the land defines the course of the war," said Alejandro Reyes, a land expert who was hired to spearhead the Agriculture Ministry's restitution efforts. "Giving back land is the difference between winning and losing the war."
Over the past quarter century, the United States has spent about $25 billion here, mostly in military-related costs, to help Colombia dismantle cocaine cartels and bring order to a lawless countryside. Violence has ebbed, and U.N. data show that the acreage dedicated to the production of the leaf used to make cocaine has fallen by half since 2001.
But until now, successive Colombian administrations and U.S. policymakers ignored a root cause of the violence. Corrupt regional bosses, paramilitary warlords and drug traffickers took advantage of the chaos to steal millions of acres of prime farmland.
The byproduct of that "counter land reform," as Reyes calls it, was the displacement of 4 million desperately poor people in 30 years, legions of whom were easy recruits for rebels and drug traffickers.
In an interview with The Washington Post, Santos said his country had "a moral debt" to victims of war atrocities and those who lost their farms, many of whom suffered at the hands of a shadowy paramilitary militia that had close ties to Colombia's military. Santos said his plans also include modernizing a near-feudal system of land tenure.
"This would be the most profound social revolution in Colombia in its history," he said.
Reacting to the government's initiative, the country's main guerrilla army hinted it might be open to negotiations. Its commander, Alfonso Cano, said in a recent statement that the land restitution program and efforts to compensate victims of political violence are "essential to a future of reconciliation" and could "contribute to a real solution to the conflict."
Since September, the government has turned over nearly 500 square miles of farmland out of the estimated 10,000 square miles stolen from poor farmers. But it has not been easy.
For one, authorities now believe that the conflict displaced families off of 25,000 square miles, about the size of West Virginia. Many who lost their land never had a title, making it hard to determine who owned what.
Those who poached land, or bought it at cheap prices after threatening the owners, registered the properties under the names of third parties. Bribes to local officials who ran land registries helped hide the identities of the new owners.
The victims were people like Jorge Quintana, 38. He sold his farm for $355 an acre, half what it was worth, after paramilitary members made him an offer he could not refuse.
"They told us, 'Get off the land,' " said Quintana, noting that the paramilitaries used his farm to train fighters and grow lucrative palm oil trees. "They said they needed it."
It is Quintana's old farm and that of dozens of other farmers here in Monterrey, a tiny speck of a town in northern Colombia, that have become something of a test case for the government.
In a speech in September, Santos told the farmers that their plight had "touched all Colombians" and that they would soon be tilling their old farms.
But five months later, the transfer of land is tied up, even though the paramilitary commanders who held sway here agreed to turn it over. The reason, advocates for the original landowners say, is that government agencies are working at cross purposes.
The Ministry of Agriculture wants the land run by a local group, Development and Peace, which is led by a Catholic Jesuit priest and has worked in the region for 15 years. But the administrator of the land, the government's anti-poverty agency, Social Action, will not make a transfer until Congress approves a land law to provide a legal framework, said Juan Carlos Zorrilla, a spokesman for the agency.
The farmers remain hopeful, said Miriam Villegas, a coordinator with Development and Peace. But she said the maddening bureaucracy has some of them quickly losing their patience.
"The president came and he said, 'This is going to be yours,' " she said. "The problem is that the farmers are getting tired of waiting."
Among those ready to occupy his old farm is Pedro Antonio Beltran, 65.
"All this runaround to give back something that is mine," he said. "Why?"
Beltran broke down in tears as he spoke about his farm, 300 acres that were brimming with crops and animals when armed men arrived a decade ago. Sell at a low price, they told him, or we will buy from your widow.
With the money he was given, he settled here in front of the main square in Monterrey and bought a small plot a few miles away. On a recent day, he fed his chickens and turkeys, as well as a 300-pound hog, and a smile crossed his face.
"All this fills me with joy," he said. "I had all this in the old farm, the same thing."