A major security operation is under way ahead of a two-day conference that will attract some of the world's most powerful politicians.
The members of the Organisation for Security and Co-operation in Europe (OSCE) will discuss several key topics in the RDS on Thursday, December 6 and Friday December 7. It is believed Mrs Clinton will also attend events in Belfast the day before.
Gardai warned a security operation will begin from 6am on Monday with no parking in or around the Simmonscourt Complex in south Dublin.
"There will be an extensive number of garda personal from the south central division at the event site," he said.
"Our Special Detective Unit will be extensively involved, the Emergency Response Unit, our operational support unit in terms of dog unit and air support, assisting both in the planning of the operation and then on the day of the events itself."
Supt O'Brien said legitimate protesters will be accommodated. "If some people choose to break the criminal law we will deal with those as appropriate," he added.
Despite road disruptions until Saturday December 8, gardai maintain Dublin - and the National Crafts and Design Fair in the RDS - will be open for business. Local residents will only get access to their homes when they show a recent utility bill or official identification.
Security will also be stepped up at hotels across the capital as the VIPs check-in.