The Green Lines are described in the Armistice agreements as temporary, pending a negotiated settlement, and specifically NOT to be regarded as permenent borders. UNSC242, which ended the 1967 war, says ecactly the same thing - borders are to be freely negotiated. So the US will have no trouble vetoing. It will not be "impossible" for the US to veto a UN resolution which violates the UN's own authority - and UNSC 242 specifically EXCLUDED the 1967 Green Lines as final borders because the Green Lines were indefensible and unstable, leading to border clashes following Arab attacks across them. An unbalanced UNSC resolution which denounces settlements but not rocket violence will be vetoed by Obama or Congress will have his ass, and he knows it. EU and its decaying ex-colonial powers have this amusing fantasy that they are going to be revived as players and decision makers who issue diktats while the US sits still and looks the other way. Won't happen. Watch.
U.S. Senator Warner supports Iran nuclear agreement, says White House (Reuters)
from the article: Arab states preparing UN resolution against Israeli settlements