Deputy Chief Constable Will Kerr told a meeting of the Scottish Police Authority (SPA) that following Brexit, the security situation is now "fundamentally different" to what it's been in the past.
He said: "Tomorrow, during the European elections, we've had to stand up four Police Support Units, that's over 100 cops. We would have never normally done that in the past. We would never normally have needed that level of support, particularly for European elections. We do now - the tone is just fundamentally different."
Police Scotland recently stood down its Brexit unit amid continuing uncertainty over Britain's withdrawal from the EU.
The force had earlier shelved plans to cut 300 officers amid security concerns linked to Brexit.