Masked men hijacked and torched a bus in Northern Ireland on Monday morning in an attack linked to British trade union opposition to the post-Brexit trade protocol.

Unionist leaders condemned the attack as counterproductive. Democratic Unionist Party leader Jeffrey Donaldson said such threats and destruction would only “strengthen the protocol in place.”

Police noted two masked and armed men stopped the bus and ordered the driver to leave, before spraying the interior of the otherwise unoccupied vehicle with fuel and set it on fire. Such road diversions, especially of buses, were common during the three decades of conflict in Northern Ireland known as the Troubles, but are rare today.

The attack on Newtownards, a predominantly Unionist town 10 miles east of Belfast, comes weeks after Donaldson warned he would withdraw his party from Northern Ireland’s inter-community government – sparking his collapse which would be followed by new elections – unless Britain obtains fundamental concessions from the EU on the application of the trade protocol in the ports of Northern Ireland.

Monday was widely seen as Donaldson’s deadline for such action. Corn Donaldson suggested that the threat of his party’s withdrawal was unlikely to materialize this month because London’s own threats to trigger Article 16 of the treaty protocol had produced “new proposals” from Brussels.

“Serious negotiations have reopened with the British government. No reasonable person could deny that this represents significant and positive progress, ”said Donaldson. “This progress has been guaranteed by political action, not by violence.”

Police said at least one of the hijackers carried what appeared to be a handgun, although there was no way to determine if the gun was real.

The hijackers reportedly told the bus driver they were protesting the protocol, but no paramilitary group claimed official responsibility for the attack.

Newtownards has been at the center of several public protests this year against the protocol. It is also a power base for the Ulster Defense Association and the Ulster Volunteer Force. Both are banned “loyalist” paramilitary groups that are internally divided over whether to stoke violence amid the unionists’ broader anti-protocol protests.

Loyalists staged 10 days of street clashes with police in April, when many rioters said they were protesting protocol as well as police and power sharing with Sinn Féin, Ireland’s main nationalist party. .