Zelensky Warns That Russian Ambitions Don’t End With Ukraine

Moscow’s gains over the besieged port city of Mariupol likely have begun to free up troops to push further west along Ukraine’s southern regions, where Russian troops have made the most progress since the start of its invasion in February.

On Saturday two Russian missiles hit an unspecified military asset and two residential buildings in the coastal city of Odessa, more than 300 miles west of Mariupol, according to a post on the city government’s Telegram social-media account. Mr. Zelensky’s chief of staff,

Andriy Yermak,

wrote on his Telegram account that at least five civilians, including an infant, were killed and 18 people wounded. Russian officials didn’t comment Saturday on any action in Odessa.

A Russian general said Friday that Moscow wanted to establish a land corridor from Mariupol to Crimea and onward to the Russian-backed territory of Transnistria, a separatist region established inside neighboring Moldova with Moscow’s help, to support Russian speakers there.

Moldova on Friday summoned Russia’s ambassador over the comments of Maj. Gen. Rustam Minnekayev, deputy commander of Russia’s Central Military District, saying they “are unfounded and contradict the position of the Russian Federation supporting the sovereignty and territorial integrity of the Republic of Moldova.”

The general’s statements, on which the Kremlin declined to comment after they aired on state media, underscored one of Kyiv’s central rallying cries for Western support in its fight against Russia: that a revisionist Russia, under President

Vladimir Putin,

is trying to re-establish a Soviet-era sphere of influence that reaches deep inside Europe.

It also highlighted how the Kremlin has sought to use the so-called separatist republics it has backed across the Caucasus region and Eastern Europe as a pretext to exert control beyond Russia’s borders.

Transnistria broke away from former Soviet Republic Moldova following its declaration of independence from the Soviet Union in 1991 in an effort to stay within the Soviet bloc. The Soviet 14th Guards Army intervened months later on the side of the separatists and have stayed in the separatist region as what Moscow calls a peacekeeping force.

Russia has made meaningful gains along Ukraine’s coast of the Azov Sea and is seeking to make further headway west on the country’s Black Sea coast. But Ukraine retains control of the port cities of Odessa, near the border with Moldova, and Mykolaiv, where it is working to push back Russian troops. An unknown number of Ukrainian forces also remain in the tunnels and underground bunkers of the Azovstal steel plant in Mariupol.

Russian strongholds in the south and east have come into renewed focus in recent weeks following Moscow’s withdrawal of troops from around Kyiv after a failed attempt to take the capital.

Ukraine’s general staff said Saturday that Russian forces have made a tactical push from the Russian-controlled separatist regions in the Donetsk and Luhansk regions in Ukraine to position themselves for an assault on Slovyansk. That city was a center of civilian disappearances and torture at the hands of Russian-backed troops later pushed out by Ukraine during the 2014 conflict in the region.

“In the Donetsk direction, the Russian enemy is conducting offensive operations along the entire line of contact,” Ukraine’s general staff said Saturday. It said Russia’s 64th Separate Motorized Rifle Guards Brigade, which Kyiv says was responsible for some of the worst atrocities against Ukrainians in the city of Bucha, had now taken positions in eastern Ukraine but had suffered heavy losses.

Those battles don’t so far amount to the concerted Russian offensive that Ukraine and Western countries expected in what Moscow has called the second phase of the war, according to military analysts. The U.K. Defense Ministry said Saturday that Russia had made no major gains in the previous 24 hours.

Russia’s Ministry of Defense said Saturday its forces had used high-precision air-based missiles to strike 25 Ukrainian armored vehicles and three weapons depots overnight. It also said it had shot down a Ukrainian Su-25 aircraft in the region of Kharkiv and destroyed 15 Ukrainian unmanned aerial vehicles.

With the battle for Donbas pitting conventional forces against each other, Ukraine is struggling to make up for its disadvantage in artillery and a shortage of Soviet-standard ammunition—one reason why Mr. Zelensky has asked the U.S. and allies to supply NATO-standard heavy weapons. Analysts say it will take weeks for Kyiv to train its forces on the Western systems and use them to full effect.

Ukraine’s military has been able to partly offset Russia’s overwhelming advantage in aircraft by using Western-supplied antiaircraft missiles, such as Stingers and Starstreaks, to down several Russian jet fighters, helicopters and drones in recent days, according to footage of wreckage posted by Ukrainian troops and verified by military analysts. Ukraine said Friday it lost an An-26B transport plane that hit a power line in the Zaporizhzhia region, leaving at least one crew member dead.

The U.S. has been the first to provide Ukraine with NATO-standard 155-mm howitzers. President Biden said Thursday that Washington’s latest $800 million military-aid package would include 72 of the towed artillery pieces in addition to 18 pledged the previous week.

On Friday, Canada said its military had also sent an unspecified number of 155-mm howitzers and antiarmor ammunition to Ukraine. Canadian Broadcasting Corp., citing a military source, reported the package would include GPS-guided Excalibur rounds, which are valued at about $112,000 per round.

French President

Emmanuel Macron

said Paris was providing Ukraine with Caesar self-propelled 155-mm artillery pieces, in an interview published Friday by the newspaper Ouest-France. The newspaper, citing military sources, reported that Paris was transferring 12 Caesars, which have a range of some 40 kilometers, equivalent to about 25 miles, and that Ukrainian soldiers would begin training Saturday in France.

—Mauro Orru contributed to this article.

Write to Thomas Grove at thomas.grove@wsj.com and Yuliya Chernova at yuliya.chernova@wsj.com