United States President Joe Biden has forcefully pledged to defend Ukraine against Russia’s invasion, announcing dozens of new air defence systems for Kyiv, as he welcomed NATO leaders for a summit in Washington, DC.

The address on Tuesday was Biden’s highest-profile policy speech since a halting performance in a debate on June 27 that raised questions about his fitness for office as well as fears that he may lose the November 5 election to his predecessor and NATO sceptic, Donald Trump.

Speaking off a teleprompter, his voice confident and strong, Biden declared that NATO was “stronger than it’s ever been in its history”. And that is a good thing, he said, “because this moment in history calls for our collective strength”.

“Autocrats want to overturn the global order” and “terrorist groups” continue to plot “evil schemes”, Biden said, while in Europe, Russian President Vladimir Putin seeks to wipe “Ukraine off the map”.

“But make no mistake, Ukraine can and will stop Putin,” the US leader said, “especially with our full, collective support. And they have our full support.”

Biden, who has so far rebuffed calls to withdraw from the presidential race, has made restoring traditional alliances abroad the centrepiece of his foreign policy. On the campaign trail, he has sought to spotlight his commitment to NATO while making the case to voters that Trump would turn his back on the alliance if he were to return to the White House.

The US president announced major steps Washington and other NATO countries are taking to beef up Ukraine’s overwhelmed air defences. He said the US, Germany, the Netherlands, Romania and Italy would provide Ukraine with the equipment for five additional strategic air defence systems.

These include four additional Patriot batteries and a SAMP/T defence system.

“In the coming months, the United States and our partners intend to provide Ukraine with dozens of additional tactical air defence systems,” he added. “All told, Ukraine will receive hundreds of additional interceptors over the next year, helping protect Ukrainian cities against Russian missiles and Ukrainian troops facing air attacks on the front lines.”