The Force and Limits of International Weapons Treaties

In some cases, Washington supports international agreements: On July 7, the White House announced that the United States has destroyed its last remaining stores of chemical weapons. The use, stockpiling and transfer of chemical weapons is prohibited in the Chemical Weapons Convention (CWC), which was drafted in 1992 and Washington ratified in 1997. The destruction of the last stocks of these ghastly weapons signals U.S. commitment to never again employ chemicals in war.

Yet, the previous day, the United States decided to send some of its remaining stores of cluster munitions to Ukraine. The use, stockpiling and transfer of cluster bombs is prohibited in the Convention on Cluster Munitions (CCM), which was adopted in 2008 and signed by 123 countries, including two-thirds of NATO allies but not Ukraine and the United States — or Russia, which has used cluster bombs since the launch of their invasion to devastating effect but little military advantage.

Countries that have not ratified a treaty are not legally bound to comply with it. Nevertheless, the entry into force of a treaty establishes a customary norm in international law that applies to non-signatories as much as to states parties.

The United States recognizes this principle: for instance, although it has not signed the United Nations Convention on the Law of the Sea (UNCLOS), it has adopted the principles of the convention and accepted it as customary international law. The State Department justifiably condemns China (a state party) for its violations of UNCLOS in the South China Sea.

Similarly, the CCM establishes an international norm against using cluster munitions, which cause widespread harm to civilians long after wars have ended due to dud rates as high as 30%. The Ukraine transfer also violates U.S. law, which states that only cluster munitions with a failure rate of less than 1% can be transferred internationally.

Proponents of the cluster munitions transfer argue that the United States should do anything necessary to help Ukraine win its war against Putin’s aggression because the implications of a Russian victory will undermine the entire international order. They claim these cluster munitions will be a force multiplier and that due to Ukraine’s low stocks of conventional artillery rounds, cluster munitions are militarily necessary. Withholding these weapons, according to these proponents, would mean the Ukrainians would run out of artillery ammunition — and lose the war. The Ukrainian defense ministry has requested the weapons and the United States has responded to this request in what a State Department spokesperson called “a very difficult decision for the administration.”

It is important to recognize that despite overwhelming American support for Ukraine’s bravery, the United States and NATO have never sent Ukraine all weapons that it asks for, notably equipment that might be used for offensive operations in Russian territory. If, hypothetically, a hard-pressed Ukrainian military concluded that it needed chemical weapons to protect its people from Russian attacks, what would the United States do?

Now that the United States no longer has a stockpile of such weapons, the question is moot. But before their destruction, Washington would likely have refused to transfer materials prohibited in the CCW, even if Ukraine believed they were necessary.

A comparison with how the United States views the difference between the use of chemical weapons and cluster munitions has roots in an earlier conflict: the Vietnam (or Second Indochina) War and its aftermath.

Southeast Asian War Legacies and International Norms

When the United States initiated the use of Agent Orange and other “rainbow herbicides” in 1961, at the request of the South Vietnamese government, neither state was a party to the 1925 Geneva Protocol on the use of chemical weapons. The Democratic Republic of Vietnam (North Vietnam) and their socialist allies raised accusations of chemical warfare, but Washington dismissed these arguments as propaganda. U.S. troops in Vietnam and South Vietnamese civilians were told that Agent Orange was harmless to human health.

With mounting evidence that the herbicides contained highly toxic dioxin, coupled with their weak military utility, the U.S. Air Force canceled the Agent Orange program in 1971. Opposition by leading U.S. scientists and the general public to the use of chemicals in warfare was a leading contributor to the Senate’s approval of the Geneva Protocol in 1975 and later U.S. ratification of the CWC.

U.S. veterans and Vietnamese veterans and civilians who were exposed to Agent Orange have faced an uphill climb to obtain treatment and compensation. The 1991 Agent Orange Act established a process for U.S. veterans to access benefits. With no similar remedy available to them, Vietnamese victims filed suit in U.S. court in 2004. One of the reasons given for the judge’s dismissal of the lawsuit was that since the United States was not a party to the Geneva Protocol or CWC at the time that Agent Orange was sprayed, arguments based on international law were invalid.     

Regardless, the postwar impacts of chemical weapons and cluster munitions have been immense. Agent Orange may have affected the health of up to 3 million Vietnamese. Over 105,000 Vietnamese, 50,000 Laotians, and 64,000 Cambodians have died or been injured from explosions of landmines and unexploded ordnance (UXO), of which cluster bombs make up the largest part — as much as 70% of all UXO in Vietnam.

The United States has never accepted legal liability for the effects of Agent Orange or of casualties resulting from landmines and UXO in Vietnam, Laos and Cambodia. Yet since the 1990s, the U.S. government and private organizations have contributed hundreds of millions of dollars to bomb clearance, survivor assistance and eventually Agent Orange remediation, contributing to stronger U.S.-Vietnam relations.

In so doing, the United States has, in the words of former Sen. Patrick Leahy, adopted “moral responsibility” for overcoming the negative consequences of the Vietnam War. U.S. humanitarian actions on Agent Orange and UXO are consistent with the spirit of the CWC, CCM and its sister convention, the Anti-Personnel Mine Ban Convention (1997). However, the United States has ratified only one of those three documents: despite bipartisan support, the CWC barely cleared the two-thirds supermajority of senators required by the U.S. Constitution to approve of international treaties.

Treaty Ratification and U.S. Leadership

The case for U.S. participation in international security treaties is both moral and practical. Moral, as U.S. leadership on arms control and humanitarian issues is consistent with American values, the nation’s founding documents and the Biden administration’s foreign policy. Practical, since U.S. compliance with treaty provisions encourages other countries to follow suit. If we do not want adversaries to use chemical weapons or torture U.S. citizens, we should publicly renounce such practices ourselves. Countries that violate norms regardless, as in the case of Russia’s invasion of Ukraine, will then be isolated, exposed and sanctioned as criminal actors.

It may be technically legal to comply selectively with certain international conventions and not others. But it is diplomatically unwise for the United States to engage in practices that it would rightfully condemn if carried out by Russia, China or any other country. Policymakers must grapple with the dilemma of whether providing a widely condemned weapon is worth the cost in civilian lives or the damage to U.S. leadership of a rules-based order.