During his time in Belgium, the White House says, Biden is scheduled to visit NATO headquarters and deliver remarks at a summit of the alliance’s leaders. He’ll also attend and deliver remarks at a G7 leaders meeting, hold a bilateral meeting with European Council President Charles Michel, and join and deliver remarks at a European Council Summit, before wrapping the day up with a news conference. Following his first leg of the trip in Brussels, Biden will travel to Warsaw, Poland.
The trip marks a crucial opportunity for Biden to reassert the United States’ leadership on the global stage, amid a war that is causing increased anxiety among eastern NATO allies. And it will be a test of what global alliances, weakened in recent years, can achieve together in the post-World War II and post-Cold War eras.
Here are five key questions for Biden’s day with world leaders in Brussels:

What does the West do next for Ukraine?

The US and NATO allies are expected to issue several new efforts during Thursday’s emergency talks, intended to punish Russia for its war on Ukraine.
NATO leaders will approve the deployments of four additional battle groups in Hungary, Romania, Bulgaria and Slovakia at their summit Thursday, US Ambassador to NATO Julie Smith said on Wednesday.
NATO leaders are expected to agree to strengthen the alliance’s posture, including by increasing NATO forces in the eastern part of the alliance, stepping up cyber defenses and scaling up allied exercises.
Biden national security adviser Jake Sullivan said on Tuesday that the administration believes that right now “they have effective posture today for what’s necessary today,” but he added that Biden and NATO allies will discuss “longer-term adjustments to NATO force posture on the eastern flank.”
US and European officials have indicated they’ll address how to reduce Europe’s dependence on Russian energy.
Sullivan said on Wednesday that the matter will be a “substantial topic of conversation” among Biden and other leaders at G7 and EU summits Thursday and is a “major priority” for them. He said leaders have weighed a “practical road map” for ending European dependence on Russian oil and natural gas. Sullivan said the US would look to increase supplies of liquified natural gas in Europe in the short term, though he did not spell out specifics of a plan.

How will Biden lead?

Thursday’s summits could serve as a moment for Biden to reassert America’s leadership in the hamstrung NATO alliance, which he vowed to restore as a presidential candidate.
There will be several speeches, as well as a news conference, where the President is expected to lay out the US’ next steps. But ahead of Air Force One’s arrival in Europe, the administration previewed a number of new efforts the US will undertake or consider to respond to Russia.
In Brussels, Biden is expected to unveil new sanctions on Russian political figures and oligarchs. And in addition to discussing NATO’s eastern flank force posture, he’ll discuss contingency plans for Russia’s potential use of chemical or nuclear weapons with the groups he meets with, Sullivan said.
The US is also weighing changes to its own military posture in Eastern Europe. Ahead of the President’s trip, the Pentagon provided the White House with a series of options for potential additional US troops in Eastern Europe, according to a US official. Biden could announce changes to the force posture following his meetings Thursday, though any announcement would depend on conversations with allies and is not finalized.
Biden is expected to announce sanctions on hundreds of Russians serving in the country’s lower legislative body, the Duma, an official familiar with the announcement said. The US had already sanctioned some members of the body, but this week’s announcement will expand the list.
Biden will also make further commitments on human rights “to respond to the growing flow of refugees” from Ukraine, Sullivan said.
There are also more symbolic measures the US is taking — on Wednesday, ahead of Biden’s arrival in Brussels, the US government formally declared that members of the Russian armed forces have committed war crimes in Ukraine.

Does Zelensky make an appearance?

Though Ukraine is not a member of NATO, leaders in the alliance have discussed whether and how President Volodymyr Zelensky could possibly participate in this week’s summit.
Since the war began, Zelensky has delivered a number of rousing virtual addresses to various governmental bodies while remaining in his home country, urging the West to do more to counter Russian forces. But the country’s lack of NATO membership has allowed member nations to limit their interventions to further defend Ukraine, which borders NATO’s eastern flank.
Zelensky has been asking Biden to visit Kyiv, suggesting it would make for a dramatic show of support, but the option was never explored at the White House. However, Biden will head to Poland, which borders Ukraine and has taken in millions of Ukrainian refugees, on Friday.

How will Putin react to the West’s united front?

The Kremlin has issued several warnings this week against NATO, suggesting Russian President Vladimir Putin is angry with people in Ukraine who want to be part of the alliance.
Kremlin spokesperson Dmitry Peskov told CNN’s Christiane Amanpour on Tuesday that Putin has not achieved his aims in Ukraine yet. Peskov, who says he’s in touch with Putin every day, said the goal remains to get rid of the military potential of Ukraine and that occupation is not among the stated aims of the operation.
When pressed about whether he is confident Putin would not use the nuclear option, Peskov responded: “If it is an existential threat for our country, then it can be used in accordance with our concept (of domestic security).”
Peskov separately warned this week that introducing a NATO peacekeeping mission into Ukraine would be “reckless” and “extremely dangerous,” after Polish Prime Minister Mateusz Morawieck said a “proposal for a peace mission in Ukraine will be formally submitted” at the NATO summit.
The US and NATO also believe that Belarus could “soon” join Russia in its war against Ukraine, US and NATO officials have told CNN, and that the country is already taking steps to do so.
“Putin needs support. Anything would help,” a NATO military official explained on Monday.
Russia maintains that it wants to be part of conversations with global alliances. Responding to unconfirmed reports suggesting that the US and Western allies were assessing whether Russia could remain in the Group of 20, Russia’s ambassador in Jakarta said on Wednesday that Putin “wants to go” to November’s G20 summit in Indonesia.

Will NATO’s actions be effective?

Biden and NATO leaders have maintained that the war in Ukraine has unified NATO member countries more than ever, but Thursday’s meetings may be a test of strength for NATO’s capabilities.
Though unified in their actions to respond to Putin, NATO has yet to deter Russia’s monthlong war in Ukraine.
An official at the Supreme Headquarters Allied Powers Europe, the headquarters of the NATO alliance military operations in Europe, told reporters on Wednesday that Putin’s war in Ukraine has put the NATO alliance and its member nations “absolutely at risk.” Another official from the headquarters said the war has created a “new reality” for NATO allies.
“From Russia, we realize that Putin and his close circle, they are absolutely reckless people. They don’t care about human life. They lie publicly to conceal their military operations. Putin has totally changed his speech toward the West, and he has a deep hatred of our societies, of our values, so we really assess that he is dangerous, and that the alliance is absolutely at risk,” the first official said on Wednesday.
Zelensky asserted earlier this month that NATO’s Article 5, the principle of collective defense, is weaker than ever. He suggested that some of the alliance’s 30 members will fail to act if Russia’s military moves beyond Ukraine’s borders because they “have intimidated themselves,” fearing another world war.