Today all went well with security (situation normal)
The union (FNV) released a press release today in dutch, freely translate it says (sorry for the google translate at certain parts);

This week at the airport the security guards will start with an action for the first action after the expiry of the ultimatum to Schiphol and security . On a yet to be determined time the security guards will hold a short work stoppage . Besides this Additionally they will inform travellers regularly about the How and why of the Actions .

Travellers suffer as little as possible from the Actions

FNV Security selects actions which approach does justice to the principles : send a signal to the board, and as little as possible suffer for the traveller/voyager and no additional Risks if it comes to safety . Additionally the approach will be build up in time: Action frequency and / or duration being raised if it takes longer when Schiphol doesn't come with a satisfactory answer . Naturally ​​every effort will be made to perform the actions orderly.

Might be best for travellers that have to go through to security the comming days/weeks to be there on time. If you cut it short and the unions decide to have a 'short' work stoppage you might miss your flight.
Please also keep in mind that over time those actions most likely will become more longer/more frequent etc.
And afaik the unions have to warn Schiphol in advance (but don't know how far in advance)

Edit: Besides screening pax they also screen crew and work at the bagagge department. So they also might 'target' your crew or luggage.