Officers want to speak to anyone who was travelling on the A449 between 1pm and 2pm on Sunday 20 August.
We received a report of a road traffic collision on the A449, northbound, between The Coldra and Usk at around 1.30pm on Sunday 20 August.
Officers attended, along with personnel from the Welsh Ambulance Service, Welsh Air Ambulance and South Wales Fire and Rescue.
The collision involved a van and an agricultural vehicle.
The driver of the van, a 27-year-old man, was taken to hospital where he later sadly died.
His next of kin have been informed and are being supported by specialist officers.
Officers investigating the collision want to speak to any motorists who were travelling on the A449 who witnessed the collision between 1pm and 2pm on Sunday 20 August or anyone with dashcam or CCTV footage to contact us.
Call 101, quoting log reference 2300279714, or send us a direct message on social media.