WARSAW — They had been among the many ultimate few phrases of a rigorously crafted speech. However they strayed removed from the fragile stability that President Biden had tried to strike throughout three days of wartime diplomacy in Europe.

“For God’s sake, this man can’t stay in energy,” Mr. Biden mentioned Saturday, his cadence slowing for emphasis.

On its face, he seemed to be calling for President Vladimir V. Putin of Russia to be ousted for his brutal invasion of Ukraine. However Mr. Biden’s aides shortly insisted that the comment — delivered in entrance of a fort that served for hundreds of years as a house for Polish monarchs — was not supposed as an enchantment for regime change.

No matter his intent, the second underscored the twin challenges Mr. Biden confronted throughout three extraordinary summit conferences in Belgium and an up-close take a look at the battle’s penalties from Poland: preserving America’s allies united towards Mr. Putin, whereas on the similar time avoiding an escalation with Russia, which the president has mentioned might result in World Conflict III.

To realize his first purpose, Mr. Biden spent a lot of the journey drawing the world’s consideration to Mr. Putin’s atrocities since he began the battle on Feb. 24. He urged continued motion to cripple the Russian financial system. He reaffirmed America’s promise to defend its NATO allies towards any risk. And he referred to as Mr. Putin “a butcher,” liable for devastating harm to Ukraine’s cities and its folks.

Dmitri S. Peskov, the Kremlin spokesman, mentioned Mr. Putin’s destiny was not within the arms of the American president. “It’s not for Biden to determine,” Mr. Peskov advised reporters after Mr. Biden completed talking. “The president of Russia is elected by the Russians.”

Whilst he made it his mission to rally his counterparts, Mr. Biden and his aides had been decided to keep away from taking actions that Mr. Putin might use as pretexts to begin a wider, and much more harmful battle.

“There’s merely no justification or provocation for Russia’s selection of battle,” Mr. Biden mentioned earlier in his speech Saturday night time. “It’s an instance one of many oldest human impulses — utilizing brute drive and disinformation to fulfill a longing for absolute energy and management.”

In closed-door discussions at NATO and with the leaders of greater than 30 nations, Mr. Biden repeatedly vowed to not ship American troops into fight towards Russia. And regardless of determined pleas for extra assist from Volodymyr Zelensky, Ukraine’s president, Mr. Biden remained against utilizing NATO or U.S. fighter jets to safe the nation’s airspace from Russian assaults.

Mr. Biden’s journey, which started Wednesday, got here at a pivotal second for his presidency and the world, amid the biggest battle in Europe since 1945 and a mushrooming humanitarian disaster. Each are testing the resolve and cooperation inside the NATO alliance after 4 years during which former President Donald J. Trump solid doubt on its relevance and pushed a coverage of America First isolationism.

For many of his foray overseas, Mr. Biden succeeded in staying on message, based on veteran overseas coverage watchers — a actuality that made his last-minute remark about Mr. Putin’s future much more putting.

“That message of unity is strictly what Putin wants to listen to to persuade him to cut back his battle goals and finish the brutality,” Charles Kupchan, a senior fellow on the Council on International Relations. “It’s what Ukrainians want to listen to to encourage them to maintain up the struggle. And it’s what Europeans want to listen to to regular their nerves and reassure them that the US is absolutely dedicated to their protection.”

And but, the president ended his journey on Saturday and returned dwelling with few concrete solutions about how or when the battle will finish — and grim uncertainty concerning the brutal and grinding violence nonetheless to return.

A prime Russian commander on Friday appeared to sign that Moscow was narrowing its battle goals, saying that capturing Kyiv, Ukraine’s capital, and different main cities was not a precedence. Col. Gen. Sergei Rudskoi, the chief of the Fundamental Operational Directorate of the Russian navy’s Normal Workers, mentioned in a public assertion that the navy would as an alternative focus “on the principle factor: the whole liberation of the Donbas,” the southeastern area that’s dwelling to a Kremlin-backed separatist insurgency.

Administration officers say a Russian withdrawal to Donbas would quantity to a outstanding failure for Mr. Putin, who has drawn worldwide scorn for his invasion and has plunged the Russian financial system into disarray below the load of world sanctions.

If Mr. Putin decides to restrict the scope of the struggle, it could pose new diplomatic challenges for Mr. Biden, who has used the horror of all-out battle to rally the world towards Russia’s aggression. That would show harder if Mr. Putin determined to maneuver a few of his forces again — whether or not as an actual retreat or a strategic feint.

For the second, nonetheless, massive parts of Ukraine stay below siege whereas the nation’s forces have mounted a fierce resistance.

On Saturday, at the same time as Mr. Biden ready to ship his speech, Russian missiles slammed into Lviv, a metropolis in western Ukraine not removed from the Polish border. The missiles hit at or close to what’s believed to be an oil storage facility, and thick black smoke billowed over the town. No less than 5 folks had been injured.

Mr. Putin’s considering remained murky as Mr. Biden boarded Air Power One on Saturday night time for the flight again to Washington, complicating his administration’s calculus because it seems to be for tactics to maintain the stress on Russia with out going too far.

All of it provides as much as a tough process for Mr. Biden, who got here into workplace decided to finish America’s 20-year battle in Afghanistan and now faces the problem of managing the response to a different battle.

He has obtained excessive marks — even from Republicans — for sending greater than $2 billion in navy and safety assist to Ukraine, bolstering its skill to struggle off Russian forces. And he has joined European leaders in imposing crippling sanctions on the Russian financial system, placing immense stress on the Russian chief’s most ardent backers.

Throughout Mr. Biden’s go to to Brussels, NATO introduced the redeployment of further forces to member nations closest to Russia, an effort that Mr. Biden mentioned would ship a message of resolve to Mr. Putin.

The president additionally introduced $1 billion in humanitarian assist for Poland and different nations who’ve taken in 3.5 million folks fleeing the combating in Ukraine. Mr. Biden mentioned the US would open its borders to 100,000 Ukrainian refugees.

“Seen American management is now not taken with no consideration in Europe,” mentioned Ian Lesser, the chief director in Brussels for the German Marshall Fund. “On this sense, the president’s journey has made a big impression.”

However the president additionally drew criticism from Mr. Zelensky, for refusing to implement a no-fly zone over Ukraine.

“Their benefit within the sky is like using weapons of mass destruction,” Mr. Zelensky advised Mr. Biden and the leaders of different NATO nations throughout their closed-door assembly on Thursday. “And also you see the results at the moment. How many individuals had been killed, what number of peaceable cities had been destroyed.”

Mr. Biden confronted the boundaries of European motion when he put to his allies the query of curbing Russia’s skill to revenue from the sale of its oil and gasoline. Europe will get a big share of its vitality from Russia, and Mr. Biden as soon as once more discovered a deep reluctance to creating any resolution to chop off that lifeline.

As an alternative, the president introduced a longer-term plan to assist wean Europeans off using Russian gasoline.

Jeremy Bash, who served as a prime adviser at each the Pentagon and the C.I.A. below former President Barack Obama, referred to as Mr. Putin’s battle a “a geopolitical earthquake” and a “once-in-a-generation contest” that has pressured Mr. Biden to adapt shortly to a quickly altering safety and diplomatic world.

“President Biden is now a wartime commander in chief waging 4 wars directly,” Mr. Bash mentioned on Saturday. “An financial battle, an info battle, probably a cyber battle, and an unprecedented oblique navy battle towards Putin. And up to now, Putin has been unable to realize a single certainly one of his goals.”

A number of of the administration’s most ardent supporters within the overseas coverage world shortly chided the president for seeming to hunt Mr. Putin’s elimination. Richard Haass, the president of the Council on International Relations, referred to as it a “dangerous lapse in self-discipline that runs threat of extending the scope and period of the battle.”

Whereas American officers nonetheless insist their purpose shouldn’t be regime change in Moscow, even the president’s prime nationwide safety advisers have made clear they need Mr. Putin to emerge strategically weakened.

“On the finish of the day, the Russian individuals are going to ask the extra basic query of why this occurred and the way this occurred,” Jake Sullivan, the president’s nationwide safety adviser, advised reporters on Air Power One on Friday, earlier than the president’s speech. “And we consider that, on the finish of the day, they’ll have the ability to join the dots.”

Mr. Sullivan added: “These are prices that President Putin has introduced on himself and his nation and his financial system and his protection industrial base due to his fully unjustified and unprovoked resolution to go to battle in Ukraine.”