Protesters are being invited to take part in a silent anti-war demonstration.
If war is declared, peace protesters have arranged to meet at points in Haywards Heath and Burgess Hill.
The demonstrations will coincide with others in the UK which will start at 5.30pm on the day war starts.
David Roberts, a member of the Mid Sussex Global Peace Campaign, said: "We invite everyone who opposes the war to join us in a silent presence. Just be there or bring candles and placards."
The protests will take place at the Peace Garden in South Road, Haywards Heath, and at the upper end of Church Walk, Burgess Hill.
Mr Roberts, who is a poet in Burgess Hill, said members of the campaign were also planning a public meeting next month.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article