Leaders from five European NATO states reaffirmed their support for the country attacked by Russia at a meeting with Ukrainian Prime Minister Denys Shmyhal in Prague.
Their main focus at a joint working dinner on Tuesday evening was the Czech plan to procure up to 800,000 artillery shells from countries outside the EU.
Ukraine can expect a first delivery of tens of thousands of 155-millimetre shells in the next few days, said Czech Prime Minister Petr Fiala.
Fifteen EU and NATO states have now pledged around €1.6 billion ($1.7 billion) for the project.
Polish President Andrzej Duda promised support for the transport of the artillery shells, and described the situation on the Ukrainian-Russian front as difficult.
Russia has the initiative and is preparing another major offensive, he said, adding that artillery plays a key role in the defence.
"For the Ukrainian people, weapons and armaments have become as crucial for survival as water, food and air," said Dutch Prime Minister Mark Rutte.
The Prague meeting was also attended by Danish Prime Minister Mette Frederiksen and Latvian Prime Minister Evika Silina.
Shmyhal said that Ukraine was preventing a repeat of 1939, when World War II broke out with Germany's invasion of Poland. "Ukraine is and will continue to be a protective shield for Europe, he vowed.