A partial truce in Afghanistan between the Taliban, American and Afghan forces is holding, US Secretary of State Mike Pompeo said Tuesday, despite insurgent attacks and US strikes against Islamic State targets.

"So far the reduction in violence is working -- imperfect, but it's working," he told reporters at a news conference in Washington.

The planned week-long detente, which has lasted four days, doesn't amount to a full ceasefire but the number of Taliban attacks has fallen dramatically. If the "reduction in violence" holds, the US and the Taliban are expected to sign a historic deal in Doha on Saturday that would see the Pentagon withdraw thousands of troops after more than 18 years of war.

Speaking on condition of anonymity, an Afghan security source told AFP Taliban attacks had dropped from an average of 75 a day to about 15 since the truce began on February 22.

But underscoring the fragility of the situation, the interior ministry said five security personnel were killed in three attacks in rural areas Tuesday. Meanwhile, US forces announced the death of four IS members in two airstrikes in Kunar province.

Pompeo said the two sides were on the cusp of an "enormous political opportunity." "Make no mistake about it: we want to make sure that those who want the status quo -- bloodshed, tears, economic challenges -- all of those people who have an interest, whether that's because of corruption or because of some ideological views, can't spoil what it is that the Afghans so richly deserve," he added