Muslim rebels waging a four-decade insurgency in the Philippines signed a historic pact with the government on Monday to end the conflict, but both sides warned the road to peace had only just begun.
President Benigno Aquino and Moro Islamic Liberation Front (MILF) chief Murad Ebrahim witnessed the signing of the accord, which aims for a final peace pact by 2016, in a ceremony at the presidential palace in Manila.
"I come in peace and to forge a partnership of peace on the basis of the framework agreement between the MILF and the Philippine government," Ebrahim said in a speech during the ceremony.
"We extend the hand of friendship and partnership to the president and Filipino people".
Aquino, who has driven the process since assuming office in 2010, also hailed the agreement as a chance to "finally achieve genuine, lasting peace".
Ebrahim became the first MILF chief to visit the presidential palace, signifying the optimism from both sides about finally ending a conflict that has claimed 150,000 lives and the priority Aquino has put on achieving peace.
Under the plan, the 12,000-strong MILF would give up its quest for an independent homeland in the southern region of Mindanao in return for significant power and wealth-sharing in a new autonomous region there.
However the MILF's leadership, the government and independent observers have all warned the path towards peace remains littered with obstacles, and that Monday's signing does not guarantee an end to the conflict.
"As the saying goes, the devil is in the details. Much work remains to be done in order to fully reap the fruits of this framework agreement," Aquino said in his speech just before the signing by both sides' chief negotiators.
The MILF's chief negotiator, Mohagher Iqbal, expressed similar caution in a press conference after the signing.
"With all the intensity, emotional attachment and substantive agreement, it is still a piece of paper. It will not implement itself," Iqbal said as he warned of tough negotiations ahead.
Muslim rebel groups have been fighting since the 1970s for full independence or autonomy in Mindanao, which they consider their ancestral homeland from before Spanish Christian colonisation of the country began in the 1500s.
The estimated four to nine million Muslims are now a minority in Mindanao after years of Catholic immigration, but they remain a majority in some areas. Muslims would be a majority in the planned new autonomous region.
The conflict has left huge areas of Mindanao, a resource-rich and fertile farming region covering the southern third of the Philippines, in deep poverty.
The MILF is the biggest and most important remaining rebel group, after the Moro National Liberation Front (MNLF) signed a peace deal with the government in 1996.
That deal led to an autonomous region in Mindanao but Aquino described it last week as a "failed experiment" because of massive corruption and worsening poverty there.
The planned new autonomous region would replace the old one, covering much of the same area but with more powers for self-rule.
The new autonomous region would have its own parliament and ability to tax its residents, while Islamic Shariah law would apply to Muslims in civil cases.
Some of the MNLF's leaders have voiced anger at seeing their power base dissolve, and have warned they may be prepared to take up arms again.
Fresh attacks by the MNLF or small Islamic groups who still want independence are among the potential obstacles to the peace process.
Another is potential opposition from Catholic politicians and business leaders. The nation's parliament, dominated by Catholics, will have to approve the laws of the new autonomous region.
However experts have said that Aquino, who is one of the most popular presidents in the country's history, may be able to convince the country's Catholic majority to support the plan.
The two sides have set 2016 as a deadline because that is when Aquino is required by the constitution to stand down after serving a single six-year term.