Mr Duterte has ordered the military to play a role in his crackdown. He has said that he also wants to grant troops powers to arrest "scalawag" police.
Armed Forces of the Philippines (AFP) chief general Eduardo Ano said the military was "ready to operate" with the Philippine Drug Enforcement Agency (PDEA).
"(The task force) is yet to be created, but we are talking about a battalion size," he told reporters late on Saturday in Baguio City, where Mr Duterte attended a military alumni homecoming.
Up to 5,000 soldiers could be mobilised under the task force, or only 500 depending on the threat, Mr Ano said.
However, he ruled out a bloody operation by the task force, unlike some of the raids conducted by the national police.
"The AFP will not do that, we will not be involved in the street, we'll not be involved in running after street pushers," Mr Ano said.
"The armed forces will help the PDEA in running after high-level drug syndicates."
The announcement came after it emerged last month that drug squad officers had killed a South Korean businessman at national police headquarters.
In his speech during the military alumni homecoming, Mr Duterte said: "I need the help of each one, especially the military, not for social control but protection (for) the citizens from the lawless, the reckless, and the selfish."
He declared his war on drugs to be "by and large successful", but added the problem was more complex than he had thought and that is why he needed the military to play a role.
The troops will only provide back-up in the campaign and not patrol the streets or play any kind of leading role, PDEA chief Isidro Lapena told Reuters earlier this month.
Mr Duterte recently suspended the national police from the anti-narcotics campaign that has killed more than 7,700 people in seven months.