Discover here the resolution on Brexit adopted by the USB during the last General Assembly :

The General Meeting of Union Syndicale Brussels, meeting on 27 June 2017 and having regard to the difficulties facing the European Union following the Brexit referendum,

Whereas Union Syndicale Brussels has a duty to defend European integration, peace, progress and the welfare of European citizens, and can therefore only regret the United Kingdom’s decision to leave the European Union;

Whereas Europe must always be built on integration, never on exclusion;

Whereas, for the time being and until a process that is likely to be long and uncertain is completed, the United Kingdom remains a full member of the European Union;

Whereas the duty of care of administrations extends to all officials and other servants, even if circumstances change subsequent to their entry into service;

Has decided:

• To express its strongest possible support to all officials and other servants who have British nationality, whether they are in service or retired, and demand that their rights enshrined in the Staff Regulations be fully respected in the event that the United Kingdom should permanently withdraw from the European Union.
• To extend this support to all officials and other servants, whether in service or retired, of other nationalities whose place of employment and/or residence is in the United Kingdom.
• To oppose firmly any move to take advantage of this process by diminishing the employment rights of all staff in the European institutions.
• To remind all the administrations that any measure affecting the rights of British staff or staff living in the United Kingdom must be negotiated with the unions and the joint committees.
• To ask all the administrations to keep staff, the Staff Committees and the unions
  updated regularly and in real time of any developments in the matter.

Read the entire text here : Resolution on Brexit