BERLIN >> President Volodymyr Zelenskyy of Ukraine compared his country’s fight against Russia to the biblical battle of David and Goliath, telling dozens of Western officials gathered in Munich for a security conference Friday that Western weapons would be the key to defeating “the Russian Goliath.”

Zelenskyy’s address came at the opening of the annual three-day Munich Security Conference, where Ukraine is dominating the discussions. Officials, who include Vice President Kamala Harris and Secretary of State Antony Blinken, are aiming to show unity. Harris will speak Saturday.

But that is likely to be tested as the war grinds on, and the cost of sustaining the Ukrainian fight with ever more and more powerful weapons against a larger opponent threatens to create strains.

Zelenskyy acknowledged the real possibility of “fatigue” among Ukraine’s allies but stressed that the “united Davids” of the free world would prevail.

“Being David is having a sling to win,” Zelenskyy said in a video message. “We do not yet have the sling.”

He said that was why weapons deliveries must be accelerated, telling the audience, “we need to hurry up.”

“There is no alternative to speed, because it is the speed that life depends on,” he said. “Delay has always been, and still is, a mistake.”

Several prominent heads of state were in attendance, including President Emmanuel Macron of France, Chancellor Olaf Scholz of Germany and Prime Minister Rishi Sunak of Britain.

The Ukrainian leader spoke as Russia has stepped up its offensive.

With battles looming, Ukraine’s allies have been working to come up with ways to provide Kyiv with the supplies it will need for the fight ahead. Already, allies have given all manner of different Western weapon systems to Kyiv’s war effort, most recently pledging to supply it with battle tanks. Having won the commitment of tanks and armored fighting vehicles in January, Ukrainian officials quickly turned to the next item on their wish list: fighter planes.

Zelenskyy expressed thanks for allies’ assistance to date but noted that he had sought support at the previous year’s conference, in the days before Russia’s invasion. “We wanted to hear, ‘Ukraine, we will be with you.’ Unfortunately, I only heard that after Russian missiles started to hit Ukrainian land,” he said.

“David defeated Goliath not by the power of conversation but by the power of actions — by the power of the sling,” Zelenskyy said. “The sling should get stronger right now so that the next year we would gather here in Munich for the postwar security conference.”

German Chancellor Olaf Scholz, who has been one of Ukraine’s main backers, renewed pledges to help but also insisted that Kyiv’s allies must not be hasty.

“For all the pressure to act that there doubtless is, in this decisive question, care must come before rushing, cohesion before solo performances,” said Scholz, who has hesitated before taking new steps to help Ukraine.

French President Emmanuel Macron endorsed Zelenskyy’s appeal.

“We must collectively be credible,” Macron told the gathering, “because it’s the only way to make Russia come back to the negotiating table in an acceptable manner and build a sustainable peace.”

The Associated Press contributed to this report.