Mediators in both the Iran and Ukraine wars have struggled to achieve meaningful ceasefires. Although the US and Iran reached an initial two-week truce on April 7, brokered by Pakistan, the agreement has been fragile from the beginning.
By May 11, Donald Trump had declared that the ceasefire was “on massive life support” and has threatened to resume military action on numerous occasions.
Meanwhile, the latest temporary ceasefire between Russia and Ukraine from May 9 to 11 seemed over before it had begun – a now familiar pattern in the four years since Russia’s full-scale invasion. Ukraine accused Russia of violating the US-mediated pause throughout the three-day period, which ended with drone attacks on Ukrainian civilian and energy infrastructure.
So why do temporary truces in Iran, Ukraine and elsewhere so often fail to last? Ceasefires are diverse in terms of what they aim to achieve, how long they are intended to last and how they try to constrain the use of force. For instance, not all ceasefires are supposed to last forever.
Agreeing to halt conflict for a period of time can keep channels of communication open and build trust and momentum for more substantive conversations. This was the aim of the April 7 ceasefire in Iran. That agreement enabled the US and Iranian delegations to come together for talks in Pakistan over a peace proposal covering Iran’s nuclear capabilities.
That those talks failed to reach a more substantive agreement was not unexpected. The two parties only held one 21-hour negotiation session, and the inexperience of the US negotiating team has been widely reported. There is also a severely low level of trust between the US and Iranian administrations. But the existence of a ceasefire, although limited, has enabled further exchanges of peace proposals between the two parties.
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However, temporary ceasefires are likely to remain so unless parties can eventually agree to something that requires greater commitment. Research drawing on the University of Edinburgh’s PA-X Peace Agreements Database of written ceasefire agreements shows that ceasefires containing longer-term commitments aimed at reducing the capacity for violence are associated with violence being suspended for longer.
These commitments could include demobilisation – the disbanding or standing down of an armed group from combat-ready status. They may also include the establishment of demilitarised zones, or the acceptance of external guarantees, international monitoring and dispute resolution mechanisms. These mostly require the involvement of mandated third parties.
Full texts of the ceasefires in Ukraine and Iran have not been published. But public statements from people involved suggest that neither agreement included strong compliance or demobilisation mechanisms, and did not involve extensive consideration of longer-term security guarantees.
When announcing the initial April 7 ceasefire, for example, Trump said the US had agreed to a limited two-week suspension of force in exchange for the Iranian reopening of the Strait of Hormuz. But he made no reference to how compliance would be monitored or enforced by a third party, or what military actions would be mutually considered a violation.
Many analysts have noted Trump’s preference for reaching quick, transactional “deals” over sustainable agreements. Others have argued that his eagerness to announce conflicts as being solved is reducing ceasefires from being a tangible step on the exit route out of conflict to “performative diplomacy”.
Samuel Corum / EPA
It is also hard to see how the international system can enforce compliance with ceasefires in the Iran and Ukraine wars. The US and Russia’s membership of the UN Security Council means either country can veto attempts by the UN to constrain their conduct by, for example, deploying an international peacekeeping force.
Indeed, the refusal of key US allies in the Gulf such as Saudi Arabia to facilitate a recent American operation to escort oil tankers passing through the Strait of Hormuz, seems to be what has sustained the April ceasefire rather than agreed ceasefire terms or official compliance mechanisms. Iran had warned that it would respond to the operation with escalation and attacks.
Complex modern conflicts
The number and type of armed groups involved in many modern conflicts also makes sustaining ceasefires complicated. The temporary April ceasefire between Israel and Lebanon, for instance, did not formally include Hezbollah – one of the key protagonists in the conflict.
Hezbollah is a non-state armed group that prevents the Lebanese state from having a monopoly on force, and has repeatedly rejected calls from Israel and the US for it to disarm. Israel claimed that airstrikes following a May 15 agreement with Lebanon to extend the ceasefire did not violate its terms. The Israelis argued that Hezbollah was not a party to the ceasefire, allowing them to target the group’s facilities.
Adding another layer of complexity is the fact that the Israel-Lebanon conflict is intimately connected to events in Iran. The Iranian regime has explicitly made reaching a peace agreement with the US conditional on there being a “lasting ceasefire in Lebanon”.
The combination of these political factors – limited agreement terms, weak third-party enforcement and complex conflict networks – suggests that the current pattern of short-term ceasefires with fragile extensions is likely to continue until the costs of conflict become too much for parties to withstand. For affected civilians, such a tipping point cannot come too soon.
