Donald Trump has pledged to end Ukraine's war with Russia after its President Volodymyr Zelenskyy reached out to the former US president to congratulate him on his Republican presidential nomination.

The two leaders spoke on Friday over the phone.

“President Zelenskyy of Ukraine and I had a very good phone call earlier today. He congratulated me on a very successful Republican National Convention and becoming the Republican nominee for President of the United States,” Trump said in a post on Truth Social, a social media post.

The call gains significance as this is his first conversation with a foreign leader after officially becoming the Republican Party’s presidential nominee. It also reflects the growing realisation among the international community of his electoral chances in the November 5 elections.

"I appreciate President Zelenskyy for reaching out because I, as your next President of the United States, will bring peace to the world and end the war that has cost so many lives and devastated countless innocent families. Both sides will be able to come together and negotiate a deal that ends the violence and paves a path forward to prosperity,” Trump wrote.

Trump said during the call Zelenskyy condemned the heinous assassination attempt on him last Saturday and remarked about the American people coming together in the spirit of Unity during these times.

In his post on X, Zelenskyy said that he spoke with Trump to congratulate him on the Republican nomination and condemn the shocking assassination attempt in Pennsylvania.

“I wished him strength and absolute safety in the future. I noted the vital bipartisan and bicameral American support for protecting our nation's freedom and independence,” he said.

“Ukraine will always be grateful to the United States for its help in strengthening our ability to resist Russian terror. Russian attacks on our cities and villages continue every day. We agreed with President Trump to discuss at a personal meeting what steps can make peace fair and truly lasting,” Zelenskyy wrote.

The 78-year-old former US president has spoken with many foreign leaders as he seeks the presidency, but his call with Zelensky is especially significant because of the election’s implications for US policy toward Ukraine and Russia.

A Trump victory could herald an abrupt change in the transatlantic support for Kyiv that President Joe Biden established.

Just days ago, Trump announced Ohio Senator J D Vance as his running mate in November's vote. The 39-year-old has in the past said “he doesn’t care what happens to Ukraine one way or the other”.