Suspension of Treaty

Suspension differs from termination: the treaty remains in force as a legal instrument, but its operation is paused, either between all parties or between certain parties only. Once the suspending circumstance ends, parties are expected to resume performance.

The governing framework is the Vienna Convention on the Law of Treaties (VCLT, 1969), particularly Articles 57–62. Grounds for suspension include:

• Article 57 – suspension in conformity with the treaty's own provisions, or by consent of all parties after consultation.
• Article 58 – suspension by agreement between some parties only, provided it is not prohibited by the treaty and does not affect other parties' rights.
• Article 60 – suspension as a response to a material breach by another party.
• Article 61 – temporary impossibility of performance.
• Article 62 – fundamental change of circumstances (rebus sic stantibus), though this is narrowly construed.

Procedural requirements in Articles 65–67 require written notification, a waiting period (normally three months unless urgent), and indication of the measure proposed and grounds invoked.

During suspension, parties are released from the obligation to perform the treaty in their mutual relations for the period in question (VCLT Art. 72), but they must refrain from acts that would obstruct the resumption of operation.

The ICJ examined suspension in the Gabčíkovo–Nagymaros Project case (Hungary/Slovakia, 1997), where Hungary's attempted suspension and abandonment of works under the 1977 treaty was found not to be justified under the VCLT grounds invoked.

Suspension is also a tool of political signalling. Russia's announced suspension of participation in the New START Treaty in February 2023 and earlier suspensions of the CFE Treaty illustrate how states use suspension to register objection without formally withdrawing. Likewise, the Treaty on Open Skies saw successive suspensions before withdrawals by the United States (2020) and Russia (2021).