The violence has been concentrated in areas where criminal gangs linked to loyalist paramilitaries have significant influence, though there is no clear evidence that it has been encouraged by these groups.
The country's Deputy First Minister Michelle O'Neill said on Thursday that the executive would be briefed on the "violence and street disorder which is causing huge distress in local communities at this time".
"While our political positions are very different on many issues, we are all united in our support for law and order and we collectively state our support for policing and for the police officers who have been putting themselves in harm's way to protect others", it added.
Throughout the negotiations on a post-Brexit trade deal with the EU, Johnson had insisted that there would not be extra customs and paperwork requirements for businesses in Northern Ireland.
Following the 2016 Brexit result, a special "protocol" was agreed that shifted checks away from the land border.
The deal has been particularly controversial in Northern Ireland, as the implementation of the Northern Ireland protocol, created to avoid a hard border between the province and the Republic of Ireland, has resulted in the introduction of customs checks on goods from Great Britain to the province.
Katy Hayward, a politics professor at Queen's University Belfast and senior fellow of the U.K.in a Changing Europe think-tank, said unionists felt that "the union is very much under threat, that Northern Ireland's place is under threat in the union and they feel betrayed by London".
Stormont Education Minister Peter Weir was responding to earlier comments from David Campbell, chairman of the Loyalist Communities Council (LCC), an umbrella group representing loyalist paramilitary groups.
Britain planning on testing Covid-19 passports at mass gatherings
She said the increases are partly due to multiple highly-transmissible variants "which we are closely monitoring". Hospitalizations are up about 3%, with an average of almost 5,000 new admissions every day.
The disturbances this week follow on unrest over the Easter holiday in unionist areas in Northern Ireland's major cities. The way forward is through dialogue and working the institutions of the Good Friday Agreement.
Northern Ireland endured 30 years of sectarian conflict that killed 3,500 people.
Hijacked cars burn at a so-called "peace wall" on Lanark Way in west Belfast, Northern Ireland on April 7th 2021.
But she also said Sinn Fein were the "real lawbreakers" - a reference to to the ongoing Bobby Storey funeral row.
There have been long-standing difficulties between the parties that share power in Northern Ireland's government, and analysts say recent political disputes have exacerbated the situation.
Northern Ireland remains in the single market for goods and applies European Union customs rules at its ports, the protocol moved the regulatory and customs border to the Irish Sea, with a series of checks, and obligatory certifications now additionally required for many goods to be shipped into the region from other parts of Great Britain, causing dissatisfaction among loyalists in Northern Ireland, who feel it creates a border between them and the rest of the UK.
On Thursday, Ireland's prime minister called for peace as well.
In Washington, the White House also expressed concern over the violence and urged calm.
"It's really easy to see how it could get worse".