Louis René Beres is professor of political science and international law at Purdue University.

From the beginning, from the moment a primal swerve toward human fragmentation in world politics first became apparent, states and empires have negotiated treaties to provide security. Strictly speaking, these formal agreements, in written form, are always fashioned and tested according to pertinent international law. Oftentimes, of course, disputes will arise whenever particular signatories should decide that continued compliance is simply no longer in their own “national interest.”

For the moment, Israel’s 1979 Peace Treaty with Egypt still remains in place. Still, any continuing regime change in Cairo could spell the “sudden death” of this agreement. The same risks apply even to the extant military governing council, should its leaders decide that the treaty with Israel should now be terminated.

Any post-Mubarak regime that would extend some governing authority to the Muslim Brotherhood, or to its proxies, could result in a prompt Egyptian abrogation. Although any such willful cessation of treaty obligations by the Egyptian side would almost certainly be in violation of The Vienna Convention on the Law of Treaties, the governing “treaty on treaties,” there is also very little that either Israel or the “international community” would be able to do in response. [See photos from the uprisings in Egypt.]

For Israel, this should bring to mind the particular dangers of Palestinian statehood. In June 2009, Prime Minister Benyamin Netanyahu first officially agreed to the creation of a Palestinian state. But, with an apparent nod to prudence, he conditioned this acceptance upon Palestinian “demilitarization.” More precisely, said the prime minister: “In any peace agreement, the territory under Palestinian control must be disarmed, with solid security guarantees for Israel.”

This agreement seemingly represented a “smart” concession, but only if there can ever be any reasonable expectations of corollary Palestinian compliance. In fact, such expectations are entirely implausible. This is the case not only because all treaties and treaty-like agreements can be broken, but because, in this specific case, any post-independence Palestinian insistence upon militarization would likely be lawful. [See a slide show of 15 post-Cold War uprisings.]

Neither Hamas nor Fatah, now bonded together in a new unity pact, would ever negotiate for anything less than full sovereignty.

International lawyers seeking to discover any “Palestine-friendly” sources of legal confirmation could conveniently cherry-pick pertinent provisions of the 1934 Convention on the Rights and Duties of States, the treaty on statehood, sometimes called the Montevideo Convention. They could apply the very same strategy of selection to the 1969 Vienna Convention on the Law of Treaties.

International law is not a suicide pact. Israel has a “peremptory” right to remain “alive.” It was proper for Mr. Netanyahu to have previously opposed a Palestinian state in any form. After all, both Fatah and Hamas still see all of Israel as part of “Palestine.”

International law need not expect Palestinian compliance with any pre-state agreements concerning armed force. This is true even if these agreements were to include certain explicit U.S. security guarantees to Israel. Also, because authentic treaties can be binding only upon states, a non-treaty agreement between the Palestinians and Israel could quickly prove to be of little or no real authority, or effectiveness. This is to say nothing of the byzantine connections between Fatah, Hamas, the Islamic Resistance Movement, and the Egyptian Muslim Brotherhood.

What if the government of a new Palestinian state were somehow willing to consider itself bound by the pre-state, non-treaty agreement? Even in these very improbable circumstances, the new Palestinian Arab government could still have ample pretext, and opportunity, to identify relevant grounds for lawful treaty termination.

Palestine could withdraw from the “treaty” because of what it regarded as a “material breach,” a purported violation by Israel that had allegedly undermined the “object or purpose” of the agreement. Or it could point toward what international law calls Rebus sic stantibus; in English, the doctrine known as a “fundamental change of circumstances.” Here, for example, if Palestine should declare itself vulnerable to previously unforeseen dangers, perhaps even from the interventionary or prospectively occupying forces of certain other Arab armies, it could lawfully end its codified commitment to remain demilitarized. [See editorial cartoons about the Middle East uprisings.]

Another factor explains why Prime Minister Netanyahu’s hope for Palestinian demilitarization remains ill-founded. After declaring independence, a new Palestinian state government could point to certain pre-independence errors of fact, or to duress, as appropriate grounds for agreement termination. The usual grounds that may be invoked under domestic law to invalidate contracts can also apply under international law, both to actual treaties, and to treaty-like agreements.

Any treaty is void if, at the time of entry, it is 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 always such a rule, “Palestine” could be fully within its lawful right to abrogate any agreement that had, before independence, compelled its demilitarization.

Mr. Netanyahu should take no comfort from any legal promises of Palestinian demilitarization. Should the government of any future Palestinian state choose to invite foreign armies or terrorists onto its territory, possibly after the original government had been overthrown by more militantly Jihadist/Islamic forces, it could do so not only without practical difficulties, but also without necessarily violating international law.

In the final analysis, the core danger to Israel of any presumed Palestinian demilitarization is more practical than legal. The Washington-driven Road Map, a one-sided plan of land for nothing, stems from a persistent misunderstanding of Palestinian history and goals. President Obama should finally acknowledge that the Palestine Liberation Organization (PLO) was formed in 1964, three years before there were any “occupied territories.”

A Palestinian state—any Palestinian state—would represent a mortal danger to Israel. This danger would not be relieved by any legal Palestinian pre-independence commitments to “demilitarize.”