Riot police, mounted officers, a force helicopter and dog units are being used in Glasgow after protesters against an Irish unity march sparked "significant disorder".
Police said the planned march through the city's Govan area, organised by the James Connolly Republican Flute Band, was met by hundreds of "disruptive" counter demonstrators at around 7pm.
The force said this lead to "significant disorder" around Govan Road, which was blocked by officers.
Chief Superintendent Mark Hargreaves said: "Police Scotland has a duty to facilitate processions and any peaceful protest, but this kind of behaviour by persons demonstrating against the parade is utterly unacceptable.
Police said a range of policing resources were in place as part of a multi-agency response.
"Specialist public order officers in full protective equipment, the mounted section, air support and dog units have been deployed, and we are using proportionate tactics to de-escalate the situation as quickly and safely as possible."
Witnesses reported smoke bombs being used.