GENEVA • In talks between Russia and Ukraine toward a possible cease-fire after three weeks of intense fighting, negotiators are exploring prospects of possible “neutrality” for Ukraine, a former Soviet republic that has been moving closer to NATO in hopes of membership — infuriating Moscow.

The discussions this week have brought a glimmer of hope of a possible way out of the bloody crisis in Ukraine — and followed an acknowledgment from Ukrainian President Volodymyr Zelensky in the most explicit terms yet that Ukraine is unlikely to realize its goal of joining the Atlantic alliance.

An official in Zelensky’s office said the talks have centered on whether Russian troops would remain in separatist regions in eastern Ukraine after the war and where borders would be. Ukraine also wants at least one Western nuclear power involved in the talks, and a legally binding document on security guarantees.

In exchange, Ukraine was ready to discuss a neutral military status, the official told The Associated Press on condition of anonymity to discuss the sensitive matter.

Russian Foreign Minister Sergey Lavrov and Vladimir Medinsky, the chief Russian negotiator, first mentioned publicly on Wednesday that the issue of a “neutral” status for Ukraine was on the table, sparking a guessing-game about what that might mean.

But even should a deal be struck, there’s no assurance it would hold: Russia, many critics say, has gravely violated international law and its own commitments by invading Ukraine in the first place.

In the view of Russian President Vladimir Putin, the West has breached what he considered its obligation not to expand NATO into Eastern Europe.

It’s about not picking sides, keeping out of binding alliances, and trying to stay out of conflict — but even supposedly “neutral” nations have their limits.

European countries often mentioned when the concept of neutrality comes up are Switzerland — which like Austria has codified neutrality into its constitution — as well as Sweden, Finland, Ireland and, once upon a time, Belgium, which is today the home of NATO.

Switzerland has generally resonated as the leading emblem of neutrality.

The Swiss have shunned alliances, refused to join the European Union, acted as an intermediary between opposing countries, and only joined the United Nations 20 years ago — even though it has hosted the U.N.’s European headquarters for decades.

But the Swiss lined up with European Union sanctions against Russia after the invasion of Ukraine. Other countries too have strayed from neutrality in the strictest sense: Swedish forces are taking part in NATO’s winter-weather exercises in neighboring Norway; Finland has long resisted joining NATO, but Moscow’s actions in Ukraine have been changing the dynamic.

Some countries — particularly those close to Russia in Central and Eastern Europe — have gravitated close to NATO and become members, and eschewed neutrality out of concern it would convey weakness and vulnerability, and that Moscow could seize on that.

Historian Leos Muller held up Austria — which has kept its distance from NATO — as a conceivable model for Ukraine.

After World War II, Austria — which before the war had been united with Nazi Germany — was occupied by forces from four Allied powers: Britain, France, the United States and the Soviet Union.

In 1955, those four powers decided to pull out their occupying forces and let Austria be independent, but only after Moscow insisted that Austria’s parliament first write into its constitution a guarantee of neutrality.

“I think that’s the solution that they are thinking about at the moment, because it worked for Austria,” said Muller, a history professor at Stockholm University and author of the book, “Neutrality in World History.”

Still, Muller doubted whether a diplomatic exit ramp can be found just yet, after so much blood has spilled on both sides in the conflict.

Enshrining the “neutrality” of Ukraine into any deal could help diminish the military threat that Russia perceives from it — especially as a possible NATO member. Ukraine insists it has no hostile intent toward Russia, but has been sidling up to the alliance to ensure its security.

For years, Russian authorities, from Putin on down, have bristled about NATO’s gradual creep eastward after the Cold War, when the Soviet-led Warsaw Pact alliance disappeared.

Estonia, Latvia and Lithuania are the former Soviet republics now in NATO.

A brief war in 2008 between Russia and Georgia, which led to the de facto excision of two Georgian territories from its national map, put Georgia’s own ambitions to join NATO into a deep freeze.

As Ukraine gravitated closer to the West, in 2014, Russia annexed the Black Sea peninsula of Crimea and pro-Russian separatists seized control of parts of eastern Ukraine in 2014 — boosting Kyiv’s desire to join NATO, even if it was admittedly a long way off. After a continued cozying-up between NATO and Ukraine, including with weapons and advisers, Russia reached a boiling point last year.

A man walks with a bicycle in a street damaged by shelling in Mariupol, Ukraine, last week. In talks between Russia and Ukraine toward a possible cease-fire after three weeks of intense fighting, negotiators are exploring prospects of possible “neutrality” for Ukraine.

the associated press