President Volodymyr Zelensky of Ukraine arrived in Washington on Tuesday with words of gratitude and praise for American support, and pleas for more weapons and fewer restrictions on using them in his country’s war against Russia.

Mr. Zelensky credited American missiles — and permission to fire them across the border into Russia — with helping his forces hold off an attack on the city of Kharkiv, stopping a Russian offensive this spring.

But he asked for other restrictions to be lifted, so that Ukraine could fire at Russian military bases hundreds of miles inside Russia to destroy aircraft that fire weapons and drop bombs that he said were killing civilians and children.

With more American assistance, he said, Ukraine can continue to strike against Russian targets in Crimea and help “push the occupiers” out of the southern part of the country.

There were questions of which version of Mr. Zelensky would show up in Washington as leaders of NATO members gathered for a summit. Last year, he flew to the NATO summit in Lithuania after making an angry social media post criticizing alliance members for failing to offer a timeline for Ukraine to join the alliance, prompting complaints from the Biden administration and other allies.

There was no sign of anger this year. Mr. Zelensky praised the United States for its early support in the war and pushed back against those who have started to think that “it’s better to delay than act.”