littering may be; vandalism I don't think so.
Straight from C341 Vandalism Act.
"act of vandalism" means —
(a) without the written authority of an authorised officer or
representative of the Government or of the government of any
Commonwealth or foreign country or of any statutory body or
authority or of any armed force lawfully present in Singapore in
the case of public property, or without the written consent of the
owner or occupier in the case of private property —(i) writing,
drawing, painting, marking or inscribing on any public property or
private property any word, slogan, caricature, drawing, mark,
symbol or other thing;(ii)
affixing, posting up or displaying on any public property or
private property any poster, placard, advertisement, bill, notice,
paper or other document; or(iii) hanging,
suspending, hoisting, affixing or displaying on or from any public
property or private property any flag, bunting, standard, banner or
the like with any word, slogan, caricature, drawing, mark, symbol
or other thing; or
(b) stealing, destroying or damaging any public property;