MOSCOW — Russian President Vladimir Putin on Saturday voiced confidence of victory in Ukraine as he oversaw a military parade on Red Square commemorating the defeat of Nazi Germany in World War II.

Security was tight in Moscow as Putin and several foreign leaders attended the parade, even as a U.S.-brokered three-day ceasefire eased concerns about possible Ukrainian attempts to disrupt the festivities.

Putin, in power for more than a quarter-century, has used Victory Day, Russia’s most important secular holiday, to showcase the country’s military might and rally support for his military action in Ukraine, now in its fifth year.

Speaking at the parade, Putin hailed Russian troops fighting in Ukraine, declaring that they “face an aggressive force that is armed and supported by the entire bloc of NATO.”

“Victory has always been and will be ours,” Putin said as columns of troops lined up on Red Square. “The key to success is our moral strength, courage and valor, our unity and ability to endure anything and overcome any challenge.”

But this year, for the first time in nearly two decades, the parade took place without tanks, missiles and other heavy weapons, aside from a traditional flyover of combat jets.

Officials said the sudden change of format was due to the “current operational situation” and pointed to the threat of Ukrainian attacks. Kremlin spokesman Dmitry Peskov said the authorities have taken “additional security measures.”

Russia declared a unilateral ceasefire for Friday and Saturday, while Ukrainian President Volodymyr Zelenskyy announced a truce which was supposed to begin on May 6, but neither of them held as the parties traded blame for continuing attacks.

U.S. President Donald Trump announced Friday that Russia and Ukraine have bowed to his request for a ceasefire running Saturday through Monday and an exchange of prisoners, declaring that the break in fighting could be the “beginning of the end” of the war.

Zelenskyy, who said earlier this week that the Russian authorities “fear drones may buzz over Red Square” on May 9, followed up on Trump’s statement by issuing a decree mockingly permitting Russia to hold its Victory Day celebrations on Saturday, declaring Red Square temporarily off-limits for Ukrainian strikes.

Peskov, the Kremlin spokesman, shrugged off Zelenskyy’s decree as a “silly joke.” “We don’t need anyone’s permission to be proud of our Victory Day,” Peskov told reporters.

Russia’s bigger and better-equipped military has been making slow but steady gains along the more than 1,000-kilometer (over 600-mile) front line. Ukraine has hit back with increasingly efficient long-range attacks, striking Russian energy facilities, manufacturing plants and military depots. It has developed drones capable of reaching targets over 1,000 kilometers (more than 600 miles) deep into Russia, far beyond its capabilities before 2022.

Russian authorities warned that if Ukraine attempts to disrupt Saturday’s festivities, Russia will carry out a “massive missile strike on the center of Kyiv.” The Russian Defense Ministry warned the civilian population there and employees of foreign diplomatic missions of “the need to leave the city promptly.” The EU said its diplomats wouldn’t leave the Ukrainian capital despite Russian threats.

Putin has used Victory Day celebrations to encourage national pride and underline Russia’s position as a global power. The Soviet Union lost 27 million people in 1941-45 in what it calls the Great Patriotic War, an enormous sacrifice that left a deep scar in the national psyche and remains a rare point of consensus in the nation’s divisive history under Communist rule.

Victory Day parades on Red Square have involved a broad array of heavy weapons — from armored vehicles to nuclear-tipped intercontinental ballistic missiles — every year since 2008. Smaller parades are held elsewhere across the country, but this time many of them have also been pared down or even canceled altogether for security reasons.

As the troops prepared to march across Red Square on Saturday, the authorities ordered restrictions on all mobile internet access and text messaging services in the Russian capital, citing the need to ensure public safety. The government has methodically tightened internet censorship and established increasingly stringent controls over online activities, causing rumblings and rare public expressions of discontent.

Malaysia’s King Sultan Ibrahim Iskandar, Laos President Thongloun Sisoulith, Kazakhstan’s President Kassym-Jomart Tokayev, Uzbekistan’s President Shavkat Mirziyoyev and Belarus’ authoritarian leader Alexander Lukashenko were set to attend the festivities in the Russian capital. Prime Minister Robert Fico of Slovakia, a European Union member, was to meet with Putin and lay flowers at the Tomb of the Unknown Soldier memorial just outside the Kremlin walls but planned to stay away from the Red Square parade.