Ahead of the United Nations secretary-general’s trip to Moscow on Tuesday to meet with Vladimir Putin, the British prime minister, Boris Johnson, has warned Antonio Guterres to “be careful” of Kremlin propaganda tactics.

The Telegraph reported that a Downing Street source said Mr. Johnson warned Mr. Guterres on Sunday that Mr. Putin will seek to manipulate his visit. Compounding the difficult task ahead for Mr. Guterres is that Ukraine’s president, Volodymr Zelensky, has very publicly assailed the UN over its inability to keep Russia in check, going so far as to suggest the Security Council dissolve itself if it fails to act. 

The Kremlin spokesman, Dmitry Peskov, said Mr. Guterres will have talks with the Russian foreign minister, Sergei Lavrov, and “will also be received by” Mr. Putin.

Earlier this week the secretary-general called for a four-day Holy Week humanitarian pause in Russia’s unprovoked war on Ukraine. That failed to materialize. Reports have surfaced that the sinking of the Moskva missile cruiser earlier this month torpedoed any imminent chances of a peace deal between Russia and Ukraine, such was Mr. Putin’s fury at the loss. 

The issue of humanitarian corridors for the safe evacuation of civilians from Ukrainian cities still under Russian bombardment will likely be high on Mr. Guterres’s agenda during his Moscow visit. 

In the meantime, top American officials pledged Monday to help ensure Ukraine wins its fight against Russia following face-to-face talks with President Zelensky in Kyiv, the Associated Press reported.

Secretary of State Blinken and Defense Secretary Austin said America had approved a $165 million sale of ammunition for Ukraine’s war effort, along with more than $300 million in foreign military financing.

“The strategy that we’ve put in place — massive support for Ukraine, massive pressure against Russia, solidarity with more than 30 countries engaged in these efforts — is having real results,” Mr. Blinken told reporters in Poland the day after meeting with Mr. Zelensky and other Ukrainian officials. “When it comes to Russia’s war aims, Russia is failing. Ukraine is succeeding. Russia has sought as its principal aim to totally subjugate Ukraine, to take away its sovereignty, to take away its independence. That has failed.” 

On a lighter note and in a sign of how after a tumultuous few months Kyiv has reclaimed its calm, Mr. Blinken had said to Mr. Zelensky, “We got used to seeing you on video around the world, but it’s great, it’s good to see you in person.”

Mr. Blinken said U.S. diplomats returning to the country likely will first re-staff the consulate in Lviv in western Ukraine before the capital. Mr. Austin said that “the world has been inspired” by Ukraine in the war and that America would continue its support.

Sunday marked the 60th day since the start of Russia’s invasion of Ukraine. Despite some recent Russian gains in the country’s eastern Donbas region, the Ukrainian counterpunches have been coming thick and fast. “Ukrainian resistance has been strong across all axes and inflicted significant cost on Russian forces,” Britain’s Defense Intelligence reported on Sunday. Time is not on Moscow’s side. Territorial advances do not come without a certain amount of exhaustion, making it tougher to hold on to those gains. 

British defense officials say the Kremlin’s decision to besiege the Azovstal steel plant in Mariupol means many Russian units will have to remain in the city and can’t be redeployed to other parts of Ukraine.

Russia’s characteristically craven attacks on civilian architecture continued with reports on Monday morning of five attacks on train stations in central and western Ukraine. The violence apparently is not stopping there: Russian officials said on Monday morning that explosions and a fire had engulfed a key Russian oil depot and a Russian military site, both in the Bryansk region well north of the Ukrainian border.

Bryansk is also an important logistics base for Moscow’s military assault on Ukraine. The Moscow Times identified the damaged spot as the Transneft-Druzhba depot, and said that the state-run oil export company’s subsidiary runs one of the world’s longest oil pipelines from Russia to Europe.