Joe Biden, the president of the United States, has made an unannounced visit to Kyiv, in a show of solidarity just days before the first anniversary of Russia’s full-scale invasion of Ukraine.

Speaking alongside President Volodymyr Zelenskyy at Mariinskyi Palace, Biden on Monday cited the fears nearly a year ago that Russian forces might swiftly seize the Ukrainian capital.

“One year later, Kyiv stands,” Biden said, jamming his finger for emphasis on his stand decorated with the US and Ukrainian flags. “And Ukraine stands. Democracy stands. The Americans stand with you and the world stands with you.”

Since the start of the war, the US has provided Ukraine with billions of dollars in security assistance. In Kyiv, Biden announced an additional $500m package, including shells for howitzers, anti-tank missiles, air surveillance radars and other aid – but no new advanced weaponry.

Zelenskyy said he and Biden spoke about “long-range weapons and the weapons that may still be supplied to Ukraine even though it wasn’t supplied before”, but he did not detail any new commitments.

The two leaders also visited together Saint Michael’s cathedral. Air-raid sirens howled over the capital as they exited the gold-domed building, but Zelenskyy and Biden continued unperturbed, proceeding to lay a wreath and hold a moment of silence at the Wall of Remembrance honouring Ukrainian soldiers.