Poland will hand over four Soviet-made MIG-29 fighter jets to Ukraine within days, President Andrzej Duda said on March 16.

The decision, together with a similar move made by Slovakia on March 17, marks a stepping up of military aid to Ukraine with a new grade of weaponry, the offering of which has so far remained controversial.

That said, the MiG-29s are unlikely to be game-changers due to the wear and tear of the 30-year-old machines and their inferiority to Russia’s SU-27s, Centre for Eastern Studies, a Polish think-tank, said in an analysis.

Ukraine’s efforts to drive the Russian invasion back are expected to intensify in the coming weeks. The Ukrainian army’s training on some of the advanced Western weapons systems is nearing completion, while weather conditions in the east and the southeast of the country are soon expected to allow ground moves on a greater scale.

“In the next few days, we are handing over four aircraft in full working order, the rest are being serviced, prepared and will likely be handed over successively,” Duda told a press conference held jointly with Czech President Petr Pavel.

The Slovak package will consist of ten fully operational MiG-29s plus three more jets without engines to serve as a source of spare parts. Slovakia will also hand over fuel as well as ground and other accessories.

The US will reimburse Slovakia with €850mn in compensation and unspecified military materiel in return for sending the jets to Ukraine.

Poland’s decision to hand over the jets “doesn’t affect and does not change our own sovereign decision-making about the provision of F-16s,” National Security Council spokesman John Kirby told reporters on March 16, according to the Washington Post.

The Kremlin said, in turn, that Poland and Slovakia sending MiG-29s to Ukraine would not affect the outcome of the “special military operation,” Russia’s name for its war in Ukraine.

But Warsaw and Bratislava may have just increased pressure on other Nato countries to revise their opposition to send Ukraine planes, just like Poland helped alter the West’s course on supplying Kyiv with tanks, some observers said.