BRUSSELS -- World leaders heard impassioned pleas Thursday from Ukrainian President Volodymyr Zelenskyy for more military aid to defend his country, and the United States announced new sanctions and humanitarian aid as officials gathered for a trio of summits to discuss next steps in countering Russia's month-old invasion of its much smaller neighbor.
The extraordinary series of summits - hosted by NATO, the Group of Seven industrialized nations and the European Union - reflected alarm that the conflict shows no sign of ending soon and could even spread beyond Ukraine's borders. As Europe faces its greatest crisis in generations, Western leaders continue the search for ways to increase pressure on Russian President Vladimir Putin while avoiding steps that could lead to a wider war on the continent.
Zelenskky, addressing the NATO gathering by video from Kyiv, called for "military assistance without limitations" as Russia is "without limits using its entire arsenal." He specifically asked for anti-air and anti-ship weapons. And although Zelenskyy thanked Western nations for support they already have provided, his frustration was clear.
He urged NATO to provide Ukraine with "1% of all your planes, 1% of all your tanks." "We can't just buy those," Zelenskyy said. "When we will have all this, it will give us, just like you, 100% security."
U.S President Joe Biden, who is attending all three summits, said more aid was on its way.
"We are committed to identifying additional equipment, including air defense systems, to help Ukraine," Biden said in a written statement after the NATO meeting.
Billions of dollars of military hardware has already been provided. A U.S. official, who requested anonymity to discuss internal deliberations, said Western nations were discussing the possibility of providing anti-ship weapons amid concerns that Russia will launch amphibious assaults along the Black Sea coast.
The White House announced that the U.S. will welcome 100,000 Ukrainian refugees and provide an additional $1 billion in food, medicine, water and other supplies.
At the same time, Washington will expand its sanctions on Russia, targeting members of the country's parliament along with defense contractors. The U.S. will also work with other Western nations to ensure gold reserves held by Russia's central bank are subjected to existing sanctions.
With Russia facing increasing international isolation, NATO Secretary-General Jens Stoltenberg warned China against coming to its rescue.
"They should join the rest of the world and clearly condemn the brutal war against Ukraine and not support Russia," either with economic or military support, he said after the closed-door meeting.
The possibility that Russia will use chemical or even nuclear weapons has been a grim topic of conversation in Brussels, but a possibility leaders were preparing for.
Biden has said that possibility is a "real threat." In addition, Kremlin spokesman Dmitry Peskov told CNN this week that Russia could consider using its nuclear weapons if it felt there was "an existential threat for our country."
A senior European diplomat said Western leaders would continue having quiet discussions on how to respond if Russia resorts to what would be the world's first use of a tactical nuclear weapon.
The Russian invasion has spurred European nations to reconsider their military spending, and Stoltenberg opened the NATO summit by saying the alliance must "respond to a new security reality in Europe."
"We gather at a critical time for our security," he said, addressing the leaders seated at a large round table. "We are united in condemning the Kremlin's unprovoked aggression and in our support for Ukraine's sovereignty and territorial integrity."
While the West has been largely unified in confronting Russia after it invaded Ukraine, there's wide acknowledgement that unity will be tested as the costs of war chip at the global economy.
The bolstering of forces along NATO's eastern flank, almost certainly for at least the next five to 10 years if Russia is to be effectively dissuaded, will also put pressure on national budgets.
"We need to do more, and therefore we need to invest more. There is a new sense of urgency and I expect that the leaders will agree to accelerate the investments in defense," Stoltenberg said before the summit.
The energy crisis exacerbated by the war will be a particularly hot topic at the European Council summit, where leaders from Spain, Portugal, Italy and Greece are hoping for an urgent, coordinated bloc-wide response. EU officials have said they will seek U.S. help on a plan to top up natural gas storage facilities for next winter, and they also want the bloc to jointly purchase gas.
German Chancellor Olaf Scholz has dismissed calls to boycott Russian energy supplies, saying it would cause significant damage to his country's economy. Scholz is facing pressure from environmental activists to quickly wean Germany off Russian energy, but he said the process will have to be gradual.
"To do so from one day to the next would mean plunging our country and all of Europe into recession," Scholz said Wednesday.
Ursula von der Leyen, head of the European Union's executive arm, said before Biden's visit that she wants to discuss the possibility of securing extra deliveries of liquefied natural gas from the United States for the 27-nation bloc "for the next two winters."
The EU imports 90% of the natural gas used to generate electricity, heat homes and supply industry, with Russia supplying almost 40% of EU gas and a quarter of its oil. The bloc is looking at ways to reduce its dependence on Russian gas by diversifying suppliers.
The U.S. is looking for ways to "surge" LNG supplies to Europe to help, said Jake Sullivan, Biden's national security adviser.
Poland and other eastern flank NATO countries will also be seeking clarity on how the U.S. and fellow European nations can assist in dealing with their growing concerns about Russian aggression as well as a spiraling refugee crisis. More than 3.5 million refugees have fled Ukraine in recent weeks, including more than 2 million to Poland.
Biden is scheduled to visit Poland on Friday, where the energy and refugee issues are expected to be at the center of talks with President Andrzej Duda.
Sullivan said Biden and fellow leaders would aim to "set out a longer-term game plan" for what forces and capabilities are going to be required for the alliance's eastern flank countries.
Four new NATO battlegroups, which usually number between 1,000-1,500 troops, are being set up in Hungary, Slovakia, Romania and Bulgaria.
Biden arrived in Brussels with Americans increasingly accepting of the need for the U.S. to help stop Putin, according to a poll from The Associated Press-NORC Center for Public Affairs Research.
But even as concern among Americans has swelled and support for a major U.S. role in the conflict strengthened in the last month, Biden's negative approval rating has not budged, the AP-NORC poll found. Few are very confident that he can handle a crisis, and a majority thinks he lacks toughness in dealing with Russia.
Biden promised voters that he had the experience to navigate a complicated international emergency like the one unfolding in Europe and his trip will be the latest test of that proposition.