The deal that has allowed the safe Black Sea export of Ukraine's grain for the past year expired on July 17 after Russia quit in a move the UN said would 'strike a blow to people in need everywhere.'

The meeting will take place at the level of ambassadors.

Moscow says it will regard F-16 fighter jets sent to Ukraine as a 'nuclear' threat because of their capacity to carry atomic bombs.

Ukraine has been pushing for rapid membership while fighting a Russian invasion unleashed in February 2022 that has killed tens of thousands and displaced millions.

The leaders were meeting at a summit in the Lithuanian capital Vilnius as Ukrainian troops struggled to make significant gains in a counteroffensive against the Russian invasion forces occupying parts of the country.

The summit will be dominated by the repercussions of Russia's invasion of Ukraine, with leaders set to approve Nato's first comprehensive plans since the end of the Cold War to defend against any attack from Moscow.

Sweden and Finland applied to join Nato last year, casting aside policies of military non-alignment that had lasted through the decades of the Cold War as Russia's invasion of Ukraine reframed security considerations.

Sweden's bid must still be approved by the Turkish parliament, and Erdogan has agreed to push for its ratification.

The 31-member Nato alliance meets in Lithuania, aiming above all to give Ukraine some kind of path to membership, but still divided over how far to go.

The messages threatens to tear at Erdogan's ties with the Kremlin, which warned ahead of the meeting that it would be watching the outcome of Zelensky's visit 'very closely'.

Stoltenberg, a former prime minister of Norway, has been the transatlantic security alliance’s leader since 2014 and his tenure had already been extended three previous times.

Sweden and Finland applied for Nato membership last year, ditching long-held policies of military non-alignment after Russia's invasion of Ukraine.