After more than two years of death and destruction, neither side in the war in Ukraine appears close to victory: Russia will not achieve its imperial conquest of Ukraine, and Ukraine will most certainly not be able to regain control of all the territory occupied by Russia. Sooner or later, both sides will have to agree to a cease-fire and come up with a peace agreement.

That is a welcome prospect. An accord will not only reduce the killing, suffering and enormous cost of the war but will also, in the long run, make Ukraine stronger and better able to defend itself and its democracy. Crucially, it will reduce the chance of a dangerous escalation.

Many in the West argue that making concessions to Russia for a peace agreement would amount to appeasing an aggressor and only encourage further attacks. But it is not appeasement. Ending the war will allow Ukraine to rearm and integrate further into Europe and the West, actually increasing deterrence. Russia has already failed to achieve its initial war aims and will need to make significant concessions of its own as part of any agreement.

The peace conference in Switzerland this weekend, convened by Ukraine to muster diplomatic support for its cause, can provide a much needed opportunity to examine whether an accord is reasonable and achievable. Russia has expressedwillingness to negotiate, though it has not been invited to the conference because Ukraine suspects that Russia will just use the meeting for show. But the host, Switzerland, envisages that Russia will be at future conferences.

No one will know how peace negotiations will fare unless the process is started. When compared with a never-ending war that is swallowing lives and resources at an alarming rate, even an imperfect settlement would be better. So, what could Ukraine reasonably hope to achieve and what kind of concessions would it have to make?

Ukraine has pledged never to cede territory. This is supported by international law that forbids the seizure of territory by force, and Ukraine should not surrender its lawful claim to its land. But to secure a lasting cease-fire, it may need to recognize that Russia has control, though not sovereignty, over portions of four Ukrainian regions and Crimea — and halt its quest to seize back occupied areas by force.

Admittedly, this would be a difficult and painful concession and should be conditional on Russia not launching any major attacks. If Russia remains peaceful, Ukraine may need to wait for a better opportunity to reclaim all its territory, like the one Germany found in 1989 when the fall of the Berlin Wall opened the way for reunification.

As part of a peace agreement, Ukraine may also have to pause its NATO application and promise not to join for a number of years, say five to 10. This is made easier because NATO members are still far from united on allowing a nation at war into the alliance, especially given fears that membership could result in a NATO war with nuclear-armed Russia. Still, it would be a major concession.

But Ukraine can still sign bilateral treaties with individual NATO members for security support — something it has already started to do, for example, with France, Germany and Britain. Future security guarantees will need to include strong provisions for supplying weapons and intelligence to Ukraine, and help to prevent cyberattacks. That said, Ukraine’s allies would probably not be allowed to place military bases on its soil.

Any peace agreement would also need strong measures to prevent another outbreak of conflict. This could involve a demilitarized zone and mutual notifications of exercises and military maneuvers. Early warning, continuous monitoring and transparency are much easier in the age of satellite surveillance, especially of the type currently provided by the United States. International inspections and a United Nations buffer force, made up of troops from non-NATO countries, would also make future incursions harder to launch.

Admittedly, an armistice or peace agreement would give Russia time to regroup and rearm its forces. But Ukraine could do likewise. It would also mean that all prisoners of war could be returned, not just in the small groups being negotiated by the parties so far. War crimes investigations and trials would proceed, however.

Most important is that a tentative peace, even if interrupted by violations, would finally give the people of Ukraine time to rebuild their lives and their country. Millions of refugees could return home and start to repopulate the depleted country. The United States could sponsor a reconstruction effort much like the Marshall Plan. Europe could lead a rebuilding and integration effort. Peace would make it easier for Ukraine to join the European Union.

There are other benefits, too. Ukraine would continue its fight against corruption, having already put a halt to the dominant role of Ukrainian oligarchs. Democratic life could resume after the end of martial law. Ultimately, successful rebuilding will demonstrate to Russians a better alternative to the dictatorship they are under. That could be Ukraine’s and the West’s greatest victory.

To make a peace deal more acceptable to Russia, it could be offered sanctions relief, contingent on compliance with the agreement. Russia could then trade its oil and gas at market prices, though Western countries could institute mechanisms for the immediate reimposition — the so-called snapback — of sanctions if needed. Russia would regain access to its withheld gold and foreign currency reserves in the West.

Violations of any future agreement can be expected, of course, but the level of violence would still be far less than the current war. And if President Vladimir Putin of Russia does escalate to full war, Ukraine will be better able to respond. Importantly, Mr. Putin has now learned a hard lesson that invading Ukraine is not an easy task and taking over the country appears impossible. In the interim, Ukraine’s allies should maintain a steady flow of arms and increase diplomatic and economic support to strengthen the country’s position at a future bargaining table.

Since Ukraine and Russia will continue to be neighbors for decades and centuries to come, the countries must come to some mutual arrangements for peaceful resolution of disputes. And if the current killing goes on for years before a settlement is reached, people will wonder why so many people had to die first. The best way to honor those killed in war is to secure a sustainable peace so that others need not make the same sacrifice.