A controversial Brexit motorway measure which led to traffic chaos at the Port of Dover is no longer in place, Kent Police said.
Operation Stack was activated so lorries could line up to enter the port, prompting miles-long queues as police checked all vehicles and passengers.
It comes after counter-terrorism police put out a national request for enhanced security checks at UK ports.
The “emergency measure” is designed to prevent gridlock on Kent’s road network.
Kent Police said in its statement all junctions of the M20 previously closed due to the operation have now been opened.
It added: “There may still be residual delays in the area while the road network returns to normal.”
Earlier, pictures showed long lines of HGVs stacked up into the busy port.
It comes after a police operation saw all vehicles and passengers since Tuesday checked as part of a wider operation in Kent and on all short strait routes.
The policing operation has now been stood down and border control checks are returning to normal, Kent Police said.
A spokesperson for Counter Terrorism Policing said: “We can confirm that a request was made on 15 September by Counter Terrorism Policing nationally for enhanced security checks to be carried out at UK ports.
“This was in relation to ongoing operational activity and this requirement has since been stood down.
“We would like to reassure the public that there is no threat to public safety in relation to this activity and thank all those affected for their co-operation and understanding.”
But the delays to transit meant huge queues started to build up into the port and the decision was made to activate Operation Stack.