The advisory opinion (which was exactly that; it has no weight in terms of int'l law) also confirmed that final borders must be determined through negotiations. Unilateral declarations by the Palestinians would violate UN Security Council resolutions and would open the door for Israel to make unilateral decisions of its own. For these reasons, the US could not support such a move at the UN. It would set a dangerous precedent that negotiations can be easily bypassed by ramming unilateral decisions through the UN. All it takes is a majority vote. Is that really how we want to world to operate?
Jordan foreign minister says to speak with Kerry on Israel-Palestinian conflict (Reuters)
from the article: Netanyahu can blame himself for decline in Israel's world standing