Prime Minister Binyamin Netanyahu agreed on Sunday to creation of a Palestinian state, but he made this acceptance dependent upon its demilitarization. "In any peace agreement," he said, "the territory under Palestinian control must be disarmed, with solid security guarantees for Israel." Although this position represents a substantial concession on his part - largely because he is now under intense pressure from US President Barack Obama - it has absolutely no chance of success. Neither Hamas nor Fatah would ever negotiate for anything less than full sovereignty. Supporters of full Palestinian statehood can find proper legal support in certain international treaties. For example, international lawyers, seeking to "discover" helpful sources of legal confirmation, could cleverly cherry-pick provisions of the (1) Convention on the Rights and Duties of States (the 1933 treaty on statehood, sometimes called the Montevideo Convention), and (2) the 1969 Vienna Convention on the Law of Treaties. Israel has the right to endure. It was correct for Netanyahu to previously oppose a Palestinian state in any form. Nonetheless, any new arguments for demilitarization will be a nonstarter. International law would not necessarily expect Palestinian compliance with prestate agreements concerning armed force. This is true even if these agreements had included certain US guarantees. Also, because authentic treaties can be binding only upon states, a nontreaty agreement could be of no real authority. BUT WHAT IF the government of a new state was willing to consider itself bound by the prestate, nontreaty agreement? Even in these circumstances, the new government would have ample pretext to identify various grounds for lawful treaty termination. It could withdraw from the "treaty" because of what it regarded as a "material breach" (a violation by Israel that had allegedly undermined the object or purpose of the agreement). Or it could point toward what international law calls a "fundamental change of circumstances." Should Palestine declare itself vulnerable to previously unforeseen dangers, perhaps even from the forces of other Arab armies, it could lawfully end its commitment to stay demilitarized. There is another factor that explains why a treaty-like arrangement obligating Palestine to accept demilitarization could quickly and legally be invalidated after independence. The usual grounds that may be invoked under domestic law to invalidate contracts also apply under international law to treaties and treaty-like agreements. This means that a state could point to errors of fact or to duress as appropriate grounds for termination. Any treaty is void if, at the time of entry, it was in conflict with a "peremptory" rule of international law, a rule accepted by the community of states as one from which "no derogation is permitted." Because the right of sovereign states to maintain military forces for self-defense is such a rule, Palestine could be within its lawful right to abrogate any agreement that had previously compelled its demilitarization. Netanyahu could take little comfort from any legal promise of demilitarization. Should the government of any future state choose to invite foreign armies or terrorists on to its territory (possibly after the original government had been overthrown by more militantly Islamic forces), it could do so not only without practical difficulties, but also without violating international law. The core danger to Israel of Palestinian demilitarization is more practical than legal. In the final analysis, the Washington-driven road map plan of land for nothing stems from a misunderstanding of codified Palestinian goals. Obama should recall that the PLO was formed in 1964, three years before there were any "occupied territories." Negotiating for demilitarization is a nonstarter. It won't make a Palestinian state any less dangerous to Israel. This is because the Palestinian side would be under no legal or other obligation to actually demilitarize. Mr. Netanyahu, such a deal won't work. The writer, professor of international law at Purdue University, is the author of many books and articles dealing with Israel and international law.