Ukrainian President Volodymyr Zelenskyy has begun a high-stakes visit to the United States during which he will present Kyiv’s plan to end the more than two-and-a-half-year-old war against invading Russian forces to US President Joe Biden as well as election rivals Kamala Harris and Donald Trump.

Zelenskyy, who will also attend the annual meeting of the United Nations on Tuesday and Wednesday, urged Ukraine’s allies to help achieve “a shared victory for a truly just peace”.

He is expected to present his peace proposals, which he has dubbed a “victory plan”, to Biden on Thursday, before later meeting Harris, who is vice president. His office has said he expects to meet Republican candidate Trump on Thursday or Friday, although no date has been officially announced.

The Ukrainian president is in the US after a summer of intense fighting: with Moscow advancing in eastern Ukraine and Kyiv occupying tracts of Russia’s Kursk region.

Zelenskyy made an unannounced stop under extraordinarily tight security at a Pennsylvania munitions plant which manufactures 155-millimetre artillery shells.

The shells are vital to Ukraine’s war effort and it has already received more than 3 million of them from the US.

“I began my visit to the United States by expressing my gratitude to all the employees at the plant,” Zelenskyy wrote in a post on X, including photos of him shaking hands with workers at the factory.

“It is in places like this where you can truly feel that the democratic world can prevail,” he wrote.

No details on Ukraine’s latest peace proposals have been made public.

Zelenskyy said Biden would be the first foreign leader to see the plan “in full” and that it would then also be presented to “all leaders of our partner countries”.

He has said that the “entire plan” will be ready by “early November”.

The proposals, he told the media on Friday, envisage “quick and concrete steps by our strategic partners”.

One of those steps, he said, was “related to strengthening Ukraine’s weapons capabilities” while another demanded a “clear place for Ukraine in the world’s security architecture”.

The 155mm shells made in the Scranton plant are used in howitzer systems, which are large guns with long barrels that can strike targets up to 15 miles to 20 miles (24 to 32km).

Zelenskyy has also been pushing the US and other allies to allow it to use Western-supplied long-range weapons to strike military targets deep inside Russia.

Biden has so far resisted, with Moscow claiming such authorisation would be akin to NATO countries being “at war” with Russia.

Zelenskyy’s visit also coincides with US preparations for a new $375m military aid package for Ukraine.

Two US officials told the Reuters news agency last week that the package would include patrol boats, additional ammunition for high-mobility artillery rocket systems (HIMARS) as well as 155mm and 105mm artillery ammunition.