The principle of irreversibility poses a paradox for arms control. On the one hand, negotiators often seek to ensure that progress made in nuclear arms control is enduring and that agreements are resilient over time. This may include the dismantlement of certain types of weapons or the elimination of weapons-usable fissile materials. Simultaneously, policymakers must seek to ensure that arms control agreements are palpable to domestic stakeholders, especially if the treaties require legislative consent, and have the flexibility to respond to changes in the security environment. This often takes the form of withdrawal clauses, giving parties the option to leave an agreement and reverse any potential gains or the underlying intent of an agreement. This paradox bears many similarities to the transparency-security tradeoff identified by Coe and Vaynman whereby, "Any deal that is transparent enough to assure that one side complies with the deal may also shift the balance of power so much that the other side reneges in order to exploit the shift". We argue that a parallel tradeoff is between political, legal, and technical measures, including verification and transparency, which can confirm irreversibility, and security concerns that will motivate states to build flexibility into agreements, making them less irreversible, i.e. more reversible.
