Ukrainian President Volodymyr Zelenskiy arrived in the United States on Sunday to attend sessions at the U.N. General Assembly and urged his partners to help achieve "a shared victory for a truly just peace."

"This fall will determine the future of this war," he said in a post on X alongside his nightly video address, delivered from his plane.

Zelenskiy made an unannounced stop in President Joe Biden's hometown of Scranton, Pennsylvania to visit a munitions plant which he said was ramping up manufacture of crucial 155-millimeter artillery shells to help the Ukraine war effort.

"It is in places like this where you can truly feel that the democratic world can prevail," Zelenskiy said in a post on X, alongside photographs of him thanking plant workers.

The Ukrainian leader's concerns about a shortage of such munitions have taken on added urgency as Russia pummels Ukraine's energy grid ahead of the critical winter months.

In his video address, Zelenskiy said Ukraine was doing everything it could, by acquiring weapons and through diplomacy, "to consolidate our partners' support and force Russia into peace."

Zelenskiy flew on to New York, where he was expected to meet heads of U.S. companies to discuss his country's energy needs as well as leaders of states and international organizations.

Zelenskiy's visit coincides with U.S. efforts to prepare a $375 million military aid package for Ukraine, breaking a months-long trend toward smaller packages for Kyiv's military operations.

Zelenskiy said he would present a "victory plan" in Ukraine's war against Russia first to Biden. He is also expected to discuss the plan with Vice President Kamala Harris in a separate meeting on Thursday, as well as with other world leaders.

Zelenskiy also hopes to meet Republican presidential candidate Donald Trump, who has called U.S. aid to its eastern European ally a waste of money and has declined to say he wants Ukraine to win. Trump has said he will probably meet with Zelenskiy this week but no date has been announced.

Trump faces Harris in the Nov. 5 U.S. election.

Two U.S. officials told Reuters on Friday that an aid package, expected to be announced this week, includes patrol boats, additional ammunition for high-mobility artillery rocket systems (HIMARS), 155- and 105-millimeter artillery ammunition, spare parts and other weapons.

The officials said the contents and size of the package could change in the coming days ahead of Biden's expected signature.

Ukrinform said Zelenskiy would speak at a UN summit on Monday, participate in Security Council meetings on Ukraine on Tuesday, and speak during the General Assembly on Wednesday.