Cracks are appearing in the Western front against Moscow, with America’s European allies increasingly divided over whether to continue shipping more powerful weapons to Ukraine, which some fear will prolong the conflict and exacerbate its economic consequences.

Diverging perceptions of Russia’s long-term threat and whether Ukraine can actually prevail on the battlefield are at the heart of the disagreement, which is dividing a group of Western European powers from the United States, the United Kingdom, and a group of mostly central and northern European nations.

The first bloc, led by France and Germany, is becoming increasingly hesitant to provide Ukraine with the offensive, long-range weapons it would require to reclaim ground lost to Russia’s armies in the country’s south and east. They are skeptical that Russia will directly threaten the North Atlantic Treaty Organization.

On the other hand, Washington, London, and a group of primarily central and northern European nations, some of which were former Soviet bloc members, see the Russian offensive as a precursor to further Russian expansion, positioning Ukraine as the front line in a larger conflict pitting Russia against the West.

The differences between the two groups, which European officials say have been growing in recent weeks as Ukraine has lost ground in its Donbas area, are becoming more vocal in public this week, as the European Union’s heads of government meet on Ukraine.

European governments have been able to agree on previously unthinkable measures to isolate Russia’s economy, including an embargo on most of the crude oil Russia sells to Europe. However, opinions on the war’s stakes and Ukraine’s chances are sharply divided.

Public statements by the leaders of France and Germany, as well as comments by officials from those countries, indicate that they are skeptical that Kyiv can expel the invaders, and they have called for a negotiated cease-fire, prompting Ukraine to complain that it is being pressured to make territorial concessions.

Instead, leaders in the Baltic states, Poland, and elsewhere argue that supplying Ukraine with increasingly sophisticated heavy weapons is critical to not only holding the line, but also reversing Russian advances and dealing Moscow the kind of blow that would deter Russian President Vladimir Putin from taking any further military action in the future.

Some Western European countries are losing interest in sustaining a war they believe is unwinnable and has reached a bloody stalemate, draining European resources and exacerbating a looming recession. In contrast, Poland and the Baltic states, which were once under Kremlin control, see themselves as the next in line for Russian imperialist expansion.

Germany has agreed to send seven pieces of heavy artillery to Ukraine but has not sent tanks. According to government estimates, Europe’s largest economy, with a population of more than 83 million, has sent military aid worth about €200 million so far—less than Estonia, which has a population of just over one million. France has sent only 12 howitzer-style cannons to Kyiv, with no tanks or aerial defenses.

Germany has also yet to replace the Polish and Czech tanks that were sent to Ukraine with German-made equipment, as agreed in a swap. A German government spokesman said this was due to lengthy procedures, including maintenance, while some Defense Ministry officials lamented a lack of political will to act more quickly.

According to a Forsa poll conducted in early May, roughly 70% of Germans support Mr. Scholz’s cautious policy. According to the poll, 46 percent of Germans believe that heavy weapon deliveries increase the risk of the war spreading beyond Ukraine. Other polls in Italy and France have revealed similar reservations.

Officials in France and Germany deny that they are doing too little or pressuring Mr. Zelensky to make concessions. French President Emmanuel Macron and Mr. Scholz, who meet with the Ukrainian president and his Russian counterpart on a regular basis, have stated repeatedly that Kyiv will decide the terms of any peace agreement.

Germany and France agree with the U.S., Canada and Western Europe regarding the war in Ukraine, said Wolfgang Schmidt, Mr. Scholz’s chief of staff and a government minister. He said there were some differences in approach between Berlin and other nations in Central and Eastern Europe, though not in their assessment of the threat posed by Mr. Putin.