MANILA (UPDATED) – President Rodrigo Duterte on Monday declared a unilateral ceasefire with leftist rebels as part of his bid to end Asia's longest running Maoist insurgency.

Duterte made the announcement in his first State of the Nation Address (SONA) and ahead of his administration's first formal talks with communist rebels on August 20.

"To the CPP [Communist Party of the Philippines], let us end decades of ambuscades, we are going nowhere and it is getting bloodier by the day. To immediately stop violence in the ground, restore peace in the communities, I am now announcing a unilateral ceasefire with the CPP-NPA-NDF effective immediately and call on...the NDF and its forces to respond," he said.

A unilateral ceasefire on the part of the government means the military will halt offensive operations against communist rebels.

The Armed Forces, for its part, said it fully supports Duterte's declaration of ceasefire. But it said government forces will not back down if attacked by communist rebels.

"The Commander-in-Chief has initiated a very bold move and we fully support him in his effort to bring sustainable & lasting peace to our whole country," said AFP spokesperson Restituto Padilla.

"The AFP will abide by the Commander-in-Chief's instruction but will remain alert, vigilant and ready to defend itself and pursue attackers if confronted by armed elements of the NPA. The government has shown its sincerity and we expect no less from the other party. Our people long for and deserve peace and we shall work diligently as we have been doing all these years to deliver just that."

CPP founder Jose Maria Sison and and National Democratic Front (NDF) peace negotiator Luis Jalandoni said the unilateral ceasefire declaration of Duterte is a welcome development.

The CPP-NPA-NDF is willing to reciprocate the move, but it wants to see the actual content of the ceasefire declaration, the actual withdrawal of troops; and if possible, have political detainees released along with the ceasefire declaration.

"I welcome President Duterte's announcement of unilateral ceasefire of the AFP and PNP in relation to the NPA. Within the hour, the NDFP will issue a positive response," Sison said.

"It is still waiting for the full text of the Duterte's ceasefire order. It also anticipates the release of the political prisoners under a general amnesty. We share with President Duterte the determination to resume the formal talks and work for a just and lasting peace."

Presidential peace adviser Jesus Dureza earlier said that some 11 detained leftist leaders will be released so they can participate in the talks.

The leftist movement's demand for the release of political detainees was one of the reasons for the breakdown of the group's talks with the administration of then-President Benigno Aquino III.

The Aquino administration argued there was no way of verifying who was qualified for release under Joint Agreement on Safety and Immunity Guarantees (JASIG), as the diskette containing their names got corrupted over time.

The JASIG is a mechanism which grants CPP-New People's Army-National Democratic Front (CPP-NPA-NDF) leaders immunity and protection while peace negotiations are ongoing.

The leftist leaders were detained for various criminal charges, but the NDF says the charges were trumped up.

The nearly half-century long Maoist campaign of the NPA, one of the world's longest running insurgencies, has claimed over 30,000 lives, according to military estimates.