The least surprising aspect of a new report claiming that President Biden lost his cool during a phone call with the Ukrainian president, Volodymr Zelensky, is how quickly Russian media seized on it. More perplexing is the little-known dynamic between the two leaders, and what the minor meltdown portends for Ukraine as the war there drags on. 

NBC first reported that it was during a call in June that Mr. Biden “lost his temper.” Citing sources familiar with the call, the network reported that Mr. Biden had “barely finished telling Zelensky he’d just greenlighted another $1 billion in U.S. military assistance for Ukraine when Zelensky started listing all the additional help he needed and wasn’t getting.”

Mr. Biden then raised his voice and reportedly told Mr. Zelensky that he could show more gratitude given the generosity of the American people and the efforts with which the U.S. military and the Biden administration have been helping Ukraine since Russia’s invasion in February. 

Prior to the call, according to the report, some top officials in Washington felt that Mr. Zelensky’s public-facing comments were focused too much on what was not being done instead of on the funds and assistance that were being provided. Following the exchange, of which it was not immediately clear if a recording was made, Mr. Zelensky is said to have offered unambiguous praise for American assistance. 

NBC also reported that the White House plans to ask Congress for about  $50 billion in additional aid to Ukraine during the lame-duck legislative session after the midterm elections in November. 

The Russian state-run news agency RIA Novosti was quick to publish NBC’s story, which inadvertently feeds into one of Moscow’s preferred narratives: that fatigue with the war is wearing down the West’s support for Ukraine.

While there is still robust, bipartisan support for Ukraine, enthusiasm from the public has lessened over time. According to a Pew Research poll, the share of American adults who are extremely or very concerned about a Ukrainian defeat is down 17 percentage points since May, falling to 38 percent by late September from 55 percent. 

With so much money and weaponry pouring into Ukraine, mostly from Washington, managing the flow is not without problems of its own. Finland’s broadcaster, Yle, reported on Sunday that according to Finnish police, many weapons that are bound for Ukraine are ending up on Europe’s black market. The head of organized crime at the Finnish police’s investigative bureau, Christer Ahlgren, told the broadcaster that military aid to Ukraine, “including assault rifles, pistols, grenades and combat drones,” had been found in several European countries, Finland included. 

Last week Washington announced a tracking program to counter the threat of the “illicit diversion” of advanced conventional weapons donated to Ukraine. Such weapons include the likes of 1,400 Stinger anti-aircraft missiles and 8,500 Javelin anti-tank missiles. The state department’s announcement read in part that “the Ukrainian government has committed to appropriately safeguard and account for transferred U.S.-origin defense equipment, although we recognize that the chaotic nature of combat can make this difficult.”

Thus far, it continued, “intense internal demand for use on the battlefield by Ukrainian military and security forces within Ukraine is assessed to be impeding black-market proliferation of small arms and guided infantry weapons such as MANPADS and ATGMs from Ukraine.”

Yet as evidenced by the tense phone call, there is still mounting pressure from all quarters and it will likely intensify as winter approaches. While Washington and Kyiv stand shoulder to shoulder in the effort to eject Russian forces from Ukraine, European unity is less assured. The EU’s statistics agency reported on Monday that annual inflation has hit a new record high of 10.7 percent in the 19 countries that use the euro. The rise is mainly fueled by soaring prices for natural gas and electricity on account of Russia’s war on Ukraine.

Growing European dissension over how and to what extent to counter the Russian threat and the ongoing need to defend war-torn Ukraine means Mr. Zelensky will find himself turning to Washington only more. If he finds the president in a good mood when they get on the phone, so much the better.