The United States Department of Defense anticipates that President Donald Trump will issue an order as early as this week to cut the number of troops in Afghanistan and Iraq in half by mid-January, CNN reported, citing two US officials.

The Pentagon has already issued a "warning order" notice to commanders to start planning the reduction of forces in Afghanistan to 2,500 troops and 2,500 in Iraq by 15 January, the report said.

Earlier this month, shortly before being "terminated" by Trump via Twitter in the wake of the election, then-Defence Secretary Mark Esper sent a classified memo to the White House warning against a rapid withdrawal of troops from Afghanistan, The Washington Post reported last week.

Trump tweeted in October that all US troops should be home by Christmas, only to be disavowed by US National Security Adviser Robert O'Brien who said that thousands of troops were "on path" to remain there into early next year.

Esper raised concerns about zeroing out US military presence in the country amid peace talks with the Taliban* insurgency, according to senior US officials, the report said. He drew Trump’s attention to a rise in violence by the Taliban and a possible danger to the remaining troops and allies.

Trump has been in a hurry to deliver on his pledge to end the longest war in US history. After the US reached a deal with the Taliban in February the number of troops was drawn down to 8,600 in July, with another 4,000 troops expected to leave in fall. By early next year the contingent may be reduced to 2,500 servicemen.

Trump replaced Esper with Director of the National Counterterrorism Center Christopher Miller.