Ukraine’s President Volodymyr Zelensky can count the past week as a successful one. He travelled through a range of European countries gathering new military and political commitments, while in Russia the drama sparked by the Wagner Group’s march on Moscow two months ago reignited after a private plane ^[1] reportedly carrying the group’s leader, Yevgeny Prigozhin, exploded ^[2] and fell out of the sky on Wednesday, just north of Moscow.

All on board the aircraft died, reportedly including Prigozhin, senior Wagner commander Dmitry Utkin ^[3], Prigozhin’s head of security Valery Chekalov ^[4], Wagner’s logistics manager and other security personnel. While there will likely never be confirmation about who was behind the explosion, there is almost no doubt that it was Russian President Vladimir Putin’s retribution ^[5] for June’s aborted mutiny.

In what was unlikely to be a coincidence, on the same day, General Sergei Surovikin ^[6], who was apparently close to Prigozhin and had not been seen in public since the mutiny, was reportedly relieved of his command of the Russian Aerospace Forces.

Putin has still been weakened by the events of June, but this will reinforce the idea in Russia that anyone who crosses Putin doesn’t survive long. Since the war started, nine generals or senior figures ^[7] who fell out with Putin have died in unexplained or dubious circumstances.

The end of Prigozhin is unlikely to be the end of Putin’s domestic challenges.

But before all that drama occurred, on 17 August, I took an 18-hour ferry ride from Helsinki to Stockholm and, as I boarded the boat, Sweden’s terrorism threat level was raised ^[8] to ‘high’ (the second highest level on a five-tier scale) for the first time since 2016. It was in response to Quran-burning protests over recent months and an assessed associated increase in terrorism threats.

However, the threat level change may also have been timed to coincide with a surprise visit ^[9] to Sweden by Zelensky two days later. There certainly appeared to be above-average helicopter traffic over Stockholm and security personnel were stationed on many street corners.

Zelensky considered the trip a success, listing 10 outcomes ^[10] of the talks with Swedish Prime Minister Ulf Kristersson. Among them were an additional security package and an announcement that Ukraine will begin production of Sweden’s CV90 armoured combat vehicle. Zelensky also announced that Sweden was training Ukrainian pilots in Swedish Saab-made Gripen fighter jets, building on agreements made in June. The Gripen is a good option for Ukraine due to its reliability ^[11] in harsh wartime conditions, but when, or whether, Ukraine will receive any Gripens is another issue. Sweden currently requires its fleet for its own defences.

The Gripen announcement was followed by several important new statements on the supply of US-made F-16 fighter jets as Zelensky’s tour continued. After Sweden, on Sunday he travelled to the Netherlands, where it was announced ^[12] that up to 42 F-16s would be transferred to Ukraine once its pilots and engineers had completed their training.

On the same day, he travelled to Copenhagen, where Prime Minister Mette Frederiksen announced that Denmark would gradually provide Ukraine with its entire fleet of 19 F-16s by 2025 as it transitioned its own air force to F-35s. On Monday, Zelensky addressed the Danish parliament, thanking them effusively for their support. I travelled to Copenhagen the next day and Zelensky’s visit still dominated the local front pages.

Despite Zelensky’s understandable enthusiasm about the announcements—since they are the first concrete commitments for the supply of F-16s—the ongoing delays in NATO’s delivery of effective weapons systems to Ukraine has had significant impacts on its ability to defend its territory against Russia’s forces.

The training of Ukrainian pilots and support personnel has now finally begun, but there is no chance ^[13] that F-16s will be in the air above Ukraine before next year. With training likely to take at least six months, including English-language instruction ^[14] on specialist terminology, the earliest that will happen is in the northern spring.

Following US President Joe Biden’s belated agreement in May ^[15] to allow the export and re-export of F-16s from its allies, a level of urgency in NATO decision-making would have allowed Ukraine to be operating F-16s by the end of this year. While there has undoubtedly been work going on in the background to make that policy a reality, a lack of commitment to prioritise Ukraine’s needs has resulted in another three months of indecision, continuing the slow drip-feed of NATO weapons that has frustrated Ukrainian political and military leaders.

Indeed, a more decisive level of support from the US and NATO over the 18 months since Russia launched its full invasion could have allowed Ukraine to make substantial inroads into the occupied territories in last year’s summer, particularly towards Melitopol ^[16], before Russia’s occupying forces had the winter to establish their full defensive lines.

The fourth-generation F-16s, when they finally enter the fray above Ukraine’s skies, won’t ^[17] give Ukraine air superiority against Russia’s fifth-generation jets. The airspace above the battlefield will remain treacherous for planes of both sides due to the lethal air defences. They will, however, give Ukraine longer-range vision and capabilities ^[18] for missile deployment and ground support, particularly in collaboration with the Patriot modern radar system.

The F-16 is also a key platform for delivering a range of missiles that can be used to destroy Russia’s air-defence systems. While the UK Storm Shadow and French SCALP missiles have been adequately launched from Ukraine’s adapted Soviet aircraft, the F-16 is specifically designed to operate with a range of NATO-designed missiles, including the game-changing AGM-158 JASSM (joint air-to-surface standoff missile).

Equipping Ukraine’s air force with F-16s will therefore allow ease of integration with NATO weapons as well as parts and maintenance from a range of NATO countries.

For NATO and Ukraine, however, the long-term significance of these decisions is that Ukraine is becoming much more embedded and integrated into the NATO architecture and supply lines. Once Ukrainian pilots and other defence personnel are familiar with NATO systems and the technical English-language instruction required for the most advanced NATO weaponry, interoperability will become easier and more natural.

As the death of Prigozhin in Russia closes one chapter for Putin, the economic, political and military challenges ^[19] associated with the invasion of Ukraine will continue to accumulate. Putin will be hoping for a Republican presidential victory ^[20] presidential victory in 2024 to reduce NATO’s support for Ukraine. It’s up to the US and other allies to quicken the delivery of NATO systems over the next 18 months to ensure that Ukraine’s legitimate territory can be recovered before that potential eventuality.