It was an inauspicious location for the signing of one of the most fateful agreements in the history of modern Ukraine.

On 5 December 1994, Ukraine’s second independent president, Leonid Kuchma, met Russian president Boris Yeltsin, US president Bill Clinton and British prime minister John Major at a business center in Budapest. They signed a memorandum on security assurances, which seemingly guaranteed the “independence and the sovereignty of the existing borders” of Ukraine. It promised that none of the signatories’ weapons “will ever be used against Ukraine, except in self-defence”.

At the time, Ukraine had the third-largest number of nuclear weapons in the world. The Budapest memorandum committed Kyiv to nuclear disarmament in exchange for financial compensation and that non-aggression pledge. By 1996, the last of Ukraine’s nuclear warheads had been sent to Russia for dismantling.

Nearly 30 years later, the Ukrainian negotiators appear naive.

A 1993 options paper prepared by Ukraine’s Ministry of Foreign Affairs says that if the country gave up nuclear weapons and signed a deal like the Budapest memorandum, its “level of security [would increase] substantially”. As a result of the guarantees, the paper said, the “threat of a first nuclear strike [from nuclear powers] disappears”.

For Ukrainians, the Budapest memorandum has been tragic.

The US State Department insisted the security promises be called “assurances” rather than binding guarantees and they have proved to be neither an assurance nor a guarantee. In fact, they were all but worthless when Russia invaded Crimea and then Donbas in 2014.

“The Budapest memorandum wasn’t worth the paper it was written on,” Andriy Yermak, Ukrainian president Volodymyr Zelenskyi’s chief-of-staff, told openDemocracy in a text message.

On 15 February 2022, less than ten days before Russia’s full-scale invasion of Ukraine, Zelenskyi addressed the Munich Security Conference, the world’s leading forum to discuss international security challenges. US President Joe Biden had warned that Russia might invade Ukraine within 24 hours. Nearly 200,000 Russian troops were massed on Ukraine’s borders and some world leaders had counselled Zelenskyi to stay home because of the risk of an imminent attack. He received a standing ovation when he stood up to speak but by the end of his speech, the applause was more subdued. Zelenskyi had denounced Western leaders for failing Ukraine.

“We don't have that [nuclear] weapon. We also have no security,” the Ukrainian president thundered.

“Therefore, we have the right to demand a shift from a policy of appeasement to ensuring security and peace guarantees.”

Zelenskyi never received those guarantees and on 24 February, Russian troops invaded, crossing into the south, east and north of the country. “It [the invasion] wouldn’t have happened if we had effective security guarantees,” says Yermak.

Nearly eight months on “the world has changed,” says Marie-Agnes Strack-Zimmerman, head of the German Bundestag’s Defence Committee. “I couldn’t have imagined then that we [Germany] would have sent them [Ukraine] so many weapons.”

As Ukraine has had some battlefield successes – Kyiv, Izyum and, perhaps soon, Kherson – the country has moved ever closer to the West and NATO, the security alliance of 30 countries mainly from North America and Europe.

The Ukraine Defense Contact Group at Ramstein, a US air force base in Germany, sends a powerful signal. Every month, Kyiv meets dozens of Washington’s allies and outlines its defence needs. In response, participants pledge coordinated deliveries.

This practical support is increasingly reflected in terminology. In NATO’s July communique, member states called Ukraine a “close partner”. A G7 statement – released after the war escalated with lethal missile strikes on Ukrainian cities on 10 October – declared that the group will “stand with Ukraine for as long as it takes”.

The language reflects individual commitments made by key decision-makers, such as German foreign minister Annalena Baerbock, according to Strack-Zimmerman of the Bundestag’s Defence Committee.

Even so, Kyiv remains concerned, according to Fabrice Pothier, policy chief to former NATO secretary general ​​Anders Fogh Rasmussen, who has been working closely with Zelenskyi’s office on near-term security guarantees strategy for Ukraine, prior to membership of NATO or the European Union. Ukraine is worried about the efficacy of arms supplies and the durability of political support, he says.

“Allies tend to be about two-three months behind Ukraine’s asks [on weapons],” Pothier told openDemocracy. Kyiv also sees allied nations’ political support as somewhat ‘ad hoc’, he added. This, even though Ukraine faces an adversary that wants to remove its government and has signalled it doesn’t recognise its right to exist as a sovereign country.

The solution proposed by Pothier and the Zelenskyi administration involves formal security guarantees from Western allies. These would be put in place before any hypothetical negotiations with Russia, which could take place once Ukrainians are ready, Pothier said.

A possible template could be Israel’s long-term strategic partnership agreements with the United States, which are renegotiated every decade.

The most recent memorandum of understanding – negotiated by the Obama administration, implemented by the Trump White House and reaffirmed by Biden this year – has the US vowing “unshakable” support for Israel’s right to self-defence. There is also large-scale military financing and technology transfer to enable Israel to maintain “a qualitative military edge” over rivals like Iran, according to a 2018 State Department press release.

In September, the Ukrainian government published the Kyiv Security Compact, which proposed measures to mobilise “the necessary political, financial, military, and diplomatic resources for Ukraine’s self-defence”. It suggested a rapid reaction force, a universal reserve comprising self-defense militias and for NATO military trainers to return to Ukrainian soil. These measures would be funded, at least partly, by partner countries, as they would help guarantee Ukraine’s ability to defend itself under the United Nations’ charter.

In effect, this would involve formalising the Ukraine Defense Contact Group at Ramstein and other measures, such as intelligence sharing and technology transfers with Western partners.

Pothier says this “is a different approach [to a mutual defence clause such as NATO’s Article 5]. One party provides all the necessary resources for the party under attack to defend itself”.

Another element of the proposed guarantees would involve countries pledging to continue with sanctions imposed on Russia from 2014. Sanctions would stay until Russia withdraws from Ukrainian soil, promises to refrain from future aggression and pays reparations.

openDemocracy understands that Ukraine has begun to talk about key security guarantees for the future to states that are backing it against the Russian invasion.

Yermak acknowledges the difficulties. “We have been told many times [that] it is impossible. But gradually, the attitude has been changing… some of our partners already support the concept.”

Western leaders such as German chancellor Olaf Scholz and former Italian prime minister Mario Draghi have signaled that they are, in principle, ready to provide Ukraine with unspecified security guarantees. (openDemocracy asked Scholz’s chief of staff, Wolfgang Schmidt, if his boss was still in favour, the question remained unanswered.) Even so, some German leaders see Berlin’s verbal commitment to Ukraine’s security as sufficient.

Strack-Zimmerman says it would be “like reading tea leaves” to speculate about the form and substance of the guarantees. “What’s certain is that Ukraine has a future in NATO once it accomplishes the necessary reforms and fulfills the conditions for membership.”

According to analysts, current European capacity, or lack of it, means the only substantial security guarantees possible for Ukraine would have to come from the United States.

But in the US, political support for the Ukrainian cause remains uncertain. Next month’s midterm Congressional elections could hand the Republican Party control of the House of Representatives and it’s notable that fewer Republicans voted for a $12.3bn Ukraine humanitarian and military aid bill in September.

“I don’t think [security guarantees] seem feasible, [because they] would require strong bipartisan Congressional support to take that on,” said Ben Hodges, former commanding general for the United States Army in Europe.

In an email exchange with openDemocracy, Hodges revealed that the US Department of Defense is “planning on a new three-star headquarters to support Ukraine training”, which he described as “a good sign of a longer-term, more substantial relationship”.

Some analysts say the debate is largely academic, since the US is unlikely to support firm guarantees while Ukraine tries to recapture all of its occupied territories, including Crimea.

“I don’t think Washington is ready to give Kyiv a blank cheque right now when it is pursuing maximalist aims,” said Sergey Radchenko, a historian and foreign policy specialist at the Johns Hopkins School of Advanced International Studies.

“Binding guarantees could be part of an overall settlement, but whether we get one depends on what happens on the battlefield. Our best scenario at this stage is a frozen conflict, like Korea in 1953. The alternatives are perpetual war, with its immense human costs. Or, Russia’s comprehensive defeat on the battlefield, fraught with unacceptable risks of nuclear escalation.”

The horrific possibility that a nuclear weapon could be used against Ukraine throws up other issues. It would be yet another breach of a clause in the Budapest memorandum. Western leaders have so far signaled it would probably trigger a non-nuclear response, with conventional weapons. Hodges has warned this might include destroying the Russian Black Sea Fleet or Russian bases in occupied Crimea. However, he stresses that he speaks in a private capacity, as he is not part of the so-called White House ‘Tiger Team’, which is planning the response to any Russian use of a nuclear weapon, tactical or high yield.

In case of a nuclear attack on Ukraine, the Biden administration would have “compelling” reasons to impose serious consequences for Russia, Hodges said. “I think the Kremlin and/or at least the [Russian] General Staff take [Biden] seriously.”

On the other side of the equation is Russia, which is not deemed a reliable party to any security guarantees given its violation of the Budapest Memorandum and the 1997 Russian-Ukrainian Friendship Treaty in 2014, and having ended the Minsk peace process with its 24 February invasion.

Current contacts between Russia and Ukraine are mostly limited to informal connections over issues such as grain exports, prisoners of war and the fate of Zaporizhzhia nuclear power plant, currently occupied by Russian forces.

But these “narrow” issues, such as the successful deal to allow Ukraine to export its grain via Turkey, could “lay the groundwork for personal contacts in the future” between people very close to the Ukrainian and Russian leaderships, a source familiar with negotiations told openDemocracy.

Thomas Rowley contributed reporting to this article.