Staff from Northern Ireland's Department of Agriculture withdrawn from Brexit checks at two ports because of claims of threats last week return to work today.
The decision to resume physical inspections of animal-based products in Belfast and Larne follows a threat assessment provided by police.
The checks were suspended on 1 February after threatening graffiti appeared in a number of loyalist areas warning that port staff could be "targets".
It was claimed that staff were being threatened by unspecified opponents of the Northern Ireland Protocol, which has resulted in inspections on some products arriving from Great Britain.
Many unionists and loyalists view this Irish Sea border as a threat to Northern Ireland’s constitutional position within the UK.
Mid and East Antrim Borough Council withdrew inspection staff from Larne Port, and DUP Agriculture Minister Edwin Poots later announced that he was withdrawing department staff from there, as well as Belfast.
European Union officials overseeing the implementation of the new checks were also withdrawn.
The council's 12 environmental health workers returned to work last Friday following a risk assessment from the PSNI.
On Monday, Chief Constable Simon Byrne said there was no credible evidence of any threat to the staff.
Police have also said there is no evidence that loyalist paramilitaries were responsible for the graffiti, or to support claims that car registrations of staff members were being recorded.
A statement said the decision was taken "after receiving the full threat assessment from the PSNI, conducting our own internal risk assessment and liaising with staff and unions to put mitigations in place".
It said all physical checks on products of animal origin at all Northern Ireland points of entry "are planned to recommence on a phased basis" from today.
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
Veterinary checks on live animals arriving in Northern Ireland were not affected by the withdrawal of staff.
The suspension impacted food and other "products of animal origin" made from meat, diary and eggs.
While inspections of online documentation and "seal checks" - to ensure seals placed on containers in ports in Britain - were still intact, physical inspections of the contents ceased.
Sinn Féin Upper Bann MLA John O'Dowd told the Stormont Assembly on Monday that the decision to suspend the checks had been based on "misinformation" and that staff had been used in "a very cruel game".
He claimed the DUP, which runs the department, did not tell staff to return to work because it suited its "agenda".
That claim was rejected by the DUP’s Gordon Lyons, who has replaced Mr Poots as agriculture minister while he recovers from cancer surgery.
He described the comments as "disgraceful".