As the Russian invasion of Ukraine enters its second year, there is endless speculation not only on how it could end but also on how it should end. What is clear is that the Ukraine conflict could go on indefinitely. The problem for the West is that time is probably on the side of the Russians. Moscow will be able to continue exerting pressure on Ukraine not only by threatening its critical infrastructure but also by interfering with its grain shipments and other exports. Russia can also threaten greater ecological damage should it, for example, allow the nuclear power plant in Zaporizhzhia to leak radiation.

Adding to the urgency is the fact that strains on NATO defense industries, increasing domestic war-weariness, or higher priorities such as deterring China could force Ukraine’s partners to reduce, if not end, their support. Should that happen, the contest will become one of endurance, which is a contest Russia could win.

So it is time to talk specifics about what a just settlement might look like. Determining those specifics requires answering three questions: 1) should Ukraine revise its military objectives to make settlement more likely; 2) at what point are the United States and NATO permitted to reduce or end assistance even if there is not a just settlement; 3) at what point are the United States and NATO permitted to escalate to bring a more rapid—and just—end to the conflict.

The proper goal of a just war is a better state of peace, which requires at a minimum the vindication of the rights of the aggressed party. To vindicate an aggressed party’s rights, also at a minimum, the aggressor must publicly end hostilities, exchange prisoners of war, apologize, demilitarize at least to the point it cannot renew hostilities, and be held accountable for war crimes. Without meeting these minimum conditions, grievances will fester and aggressors will buy time to rebuild military capability and renew hostilities. However, if one accepts that Ukraine, even with foreign assistance, will not realize its goal of restoring its full sovereignty, then even this minimal standard may not be realistic.

Moreover, even if Ukraine’s goals are realistic, it must also consider the cost of attaining them. As Ukraine liberates more territory, Russian president Vladimir Putin will become increasingly desperate. Even if he does not use nuclear weapons, the Russian military will very likely continue its indiscriminate attacks against civilians and critical civilian infrastructure to force Ukrainian president Volodymyr Zelenskyy to negotiate. Moreover, given the expected resistance by Russian and separatist forces, the occupied areas will also experience significant destruction with any Ukrainian military operation to liberate them.

These points do not suggest that Ukraine should offer to negotiate terms now. Ending the war on any terms favorable to Russia would likely incentivize future aggression and set the stage for a renewal of hostilities when the Russians believe they have sufficiently recovered. If nothing else, Russia will be in a position to continue provoking Ukraine and the West, leading to further instability.

What these points do suggest, however, is that Ukraine should first consider under what conditions continued fighting will become either ineffective or disproportionate. Second, they should consider what conditions they can offer that Russia will accept while establishing a better, if not optimal, state of peace. This may sound like appeasement, but it does not have to be.

Thus, the answer to the first question posed at the outset—should Ukraine revise its military objectives—is provisionally “no.” But getting to a solution that the Russians can accept requires putting Moscow in a position where accepting a settlement and ceasing hostilities is preferable for them to continue fighting. Getting to that point will likely require greater Ukrainian military success before any diplomatic initiative has a chance of success.

To make the Russians better off if they stop fighting, the United States and NATO should consider addressing their security concerns, especially regarding NATO expansion. In the past, NATO has refused to offer such guarantees on the principle of respecting state sovereignty. However, given the costs of fighting and the urgency to resolve the conflict, compromising on this principle seems reasonable and low. For example, such an agreement does not prevent the United States and NATO from providing Ukraine with security guarantees should hostilities renew. NATO leaders should also continue efforts to admit Finland and Sweden as a cost for initiating hostilities in the first place and make it clear to the Russians that the alliance will continue to expand, and will admit Ukraine, should Russia not cease hostilities and negotiate a settlement.

The answer to the second question (i.e, at what point can the United States and NATO reduce or end their assistance even without a just settlement) is that the United States and NATO should continue to assist Ukraine until Russia is ready to negotiate a minimally just settlement. Even if the fighting does stop, Ukraine will need to continue to improve its military capabilities to deter Russia from trying again. The difficulty with this response, of course, is that it ignores certain political and economic realities. The first is that support to Ukraine has strained U.S. and NATO defense industries, which must significantly increase the production of critical materials not just to keep Ukraine in the fight but also to allow the West to maintain its deterrent threat against other adversaries like China. The second is that domestic politics in each of these countries could result in an abrupt end to assistance. In the United States, for example, there is a movement in Congress to end assistance and use these funds to improve the U.S. economy. Should the economy worsen, this argument will seem more compelling.

The morally obvious response here is for Western political leaders to remain resolute. Should the United States and NATO abruptly reduce assistance to the point where Ukraine cannot sustain the fight, the blame for the resulting injustice will partially lie with them. To avoid reaching the point where assistance to Ukraine is no longer politically viable, the United States and NATO should consider how much assistance they would provide to avoid a Ukrainian defeat and provide that now rather than providing it piecemeal in reaction to Russian successes. While the United States and Germany have recently announced their intention to provide modern battle tanks and better air defense systems, this assistance comes a year after the war started and its effects will take some time as Ukrainian crews will have to be trained on the new equipment.

While it may have made some ethical sense to limit assistance to Ukraine in the beginning to avoid escalation, that is no longer the case. If time is on the Russian side, providing assistance in reaction to Russian successes is a recipe for failure. This point does not entail giving the Ukrainians a blank check or undermining the necessity to manage escalation. However, it does suggest that it makes sense to provide now all the assistance one would eventually provide later should the tide turn more in the Russian favor.

This point naturally segues into the third question regarding escalation by the United States and NATO to bring a more rapid end to the conflict. Doing so, of course, increases the chances of direct conflict between Russia and NATO forces. Moreover, unilateral escalation by the United States and NATO will play into Putin’s narrative of NATO as a security threat, which will strengthen his hand domestically and make it more difficult to isolate him internationally.

Having said that, as Russia escalates, as it has done with attacks on civilians, the United States and NATO should find ways to increase costs to Russia as well as assistance to Ukraine to mediate the effects of that escalation. Doing so will underscore Western resolve while undermining the Russian narrative and its ability to build international support.

In considering what one should do, one first must establish what will happen if one does nothing. At current levels of assistance and Ukrainian military capability, the conflict will likely freeze. Such a freeze favors the Russians, who will continue threatening Ukraine while it consolidates its gains in the east, making their annexation a fait accompli. On the other hand, giving Russia a way out does not necessarily entail abandoning the vindication of Ukraine’s right or the demands of a better state of peace. It just means finding other ways to impose them. Thus, the ethics of conflict termination, as described here, suggest the following path to a just termination of the conflict.

First, Ukraine should continue to fight, and the United States and NATO should continue to provide assistance as long as the former’s military goals are feasible and the means to achieve them are proportionate.

Second, as long as Russia fails to return occupied Ukrainian territory, the United States and NATO should continue to impose sanctions and other costs to incentivize meaningful participation in negotiations.

Third, to ensure Russia is not able to exploit any pause a frozen conflict allows, the United States and NATO should continue military cooperation with Ukraine to improve its ability to defend itself in the future. The United States and NATO should also consider offering Zelenskyy the security guarantees he has asked for to further deter future Russian aggression.