This morning I was met with a sea of orange. There were lots of police officers setting up for a protest around the Binnenhof (parliament offices in The Hague). Reports say that at its height there were 1400 police officers on hand. I even received an email from the American consulate — basically they send out emails to interested citizens about any protest that happens in Amsterdam or The Hague. In this case the police were protesting for better pay (a 3.3% increase) and a lowering of the retirement age which currently stands at 67 years.

The beginnings of the sea of orange – there were of course many more police around the corner by the Binnenhof and Buitenhof
The email also clarified who was wearing what – police wearing an orange vest over their uniform were protesters. Police wearing a red vest over their uniform were protest leaders. And finally you also had active, on-duty police officers wearing just their police uniform.
Here is an article in Dutch and an article in English.