Colombia’s government and the Revolutionary Armed Forces of Colombia, known as FARC, signed a modified peace agreement on Saturday, a month after the country’s voters rejected a proposed truce. The two sides have been at war for more than 50 years. “We are convinced that ... this document signals a viable and possible way to end so many decades of conflict,” said Humberto de la Calle, the government’s chief negotiator, adding: “its acceptance will not be unanimous.” Colombia’s Congress, rather than its voters, will decide whether to approve the new agreement.