The United States, in coordination with its G-7 and European Union allies, is expected to announce on Wednesday a "sweeping new package of sanctions" that will impose significant costs on Russia and send it further down the road of economic, financial, and technological isolation, sources familiar with the plan told ABC News.

The plan is expected to include a ban on all new investments in Russia, boost sanctions on financial institutions and state-owned enterprises in Russia and impose sanctions on Russian government officials and their family members, the sources said.

The measures are intended to degrade key instruments of Russian state power, impose acute and immediate economic harm on Russia and hold accountable the Russian kleptocracy that funds and supports Russian President Vladimir Putin’s war.

"These measures will be taken in lockstep with our allies and partners, demonstrating our resolve and unity in imposing unprecedented costs on Russia for its war against Ukraine," one of the sources told ABC News.

-ABC News' Molly Nagle

An estimated 11 million people have been evacuated from Ukraine since Russia invaded the country on Feb. 24, the U.N. International Organization on Migration said Tuesday.

The organization also reported that more than 7.1 million people have been displaced within Ukraine as of April 1. That figure comes on top of the one from the U.N. High Commissioner for Refugees showing more than 4 million people have fled abroad.

The International Organization on Migration said more than 2.9 million people still in Ukraine are actively considering "leaving their place of habitual residence due to war."

An ABC News analysis of videos and satellite imagery confirms that some of the bodies seen lying in the streets of Bucha were there as early as March 19, when the Ukrainian city was still occupied by Russian forces, contradicting Russia's claims that the scene was "staged" after its troops left.

As Ukrainian authorities regained control over Bucha, northwest of Kyiv, gruesome images emerged earlier this week showing numerous bodies of dead civilians -- some shot at close range and with their hands bound -- strewn across streets and in mass graves. Russia has denied responsibility, calling the footage "fake" and saying that all of its units withdrew completely from Bucha around March 30.

However, satellite images provided by Maxar Technologies show that at least five of those bodies had been on the street in Bucha since March 19, when Russia said it still occupied the town. ABC News' Visual Verification team compared the satellite imagery to videos of the same scene posted on Twitter by Ukrainian authorities on April 2, as well as footage taken by ABC News journalists in Bucha on April 4.

The satellite imagery of Bucha in March was first reported by The New York Times.

-ABC News' Alice Chambers

In an address to the United Nations Security Council on Tuesday, Ukrainian President Volodymyr Zelenskyy laid out the atrocities he said were committed by Russian forces in Bucha, including women shot in front of their homes and raped in front of their children.

"There is not a single crime they would not commit," Zelenskyy told the council via a live video feed from Kyiv.

Zelenskyy proposed a summit to reform the world’s global security apparatus, listing a number of major conflicts since World War II he said the U.N. Security Council had failed to prevent.

He said Russia's actions in Bucha, a town northwest of the Ukrainian capital, are no different from other acts of terrorism.

"Here it is done by a member of the United Nations Security Council destroying internal unity borders, countries," Zelenskyy said.

He accused Russia of "pursuing a policy to kill ethnic and linguistic diversity."

Zelenskyy went on to criticize the council for failing to provide security to Ukraine, saying, the U.N. "simply cannot work effectively."

"If this continues, countries will have to rely on their selves, not (the) international community," Zelenskyy said. "The U.N. will be ready to close. Do they think the time of the U.N. is gone? If no, then the U.N. must act immediately."

Zelenskyy added, "accountability must be inevitable."

Telling the council he was speaking on behalf of the deceased, Zelenskyy detailed in graphic detail the horrors found in Bucha, describing them as "the most terrible crimes we have seen since the end of World War II.“

"The Russian military searched for and purposefully killed anyone who served our country. They killed –-- shot and killed women outside their houses when they just tried to call someone who is alive. They killed entire families, adults and children, and they tried to burn the bodies," Zelenskyy said. "I am addressing you on behalf of the people who honor the memory of the deceased, every single day in the memory of the civilians who died, who were shot and killed in the back of their head after being tortured, some of them were shot on the streets. Others were thrown into the wells, so they died. They are in suffering."

Noting Russia's veto power on the council, Zelensky proposed the council remove Russia's power so it "cannot block decisions against its own aggression" or else "dissolve yourselves altogether."

Zelenskyy's address was met with applause by the members of the council.

All Russian troops have left the Ukrainian cities of Kyiv and Chernihiv, withdrawing north toward the borders of Belarus and Russia to consolidate before likely redeploying to the Donbas region in eastern Ukraine, a senior U.S. defense official told reporters Wednesday.

But even with the Russians gone, the territory remains treacherous.

"There are some indications that they left behind mines and things like that, so the Ukrainians are being somewhat careful in some areas north of Kyiv as they begin to clear the ground and clear the territory and re-occupy it," the official said.

While the U.S. hasn't yet seen these troops redeploy elsewhere in Ukraine, it'll likely happen soon, according to the official. Ukrainian forces are preparing for a major fight in Donbas, the official said.

The official also said the Pentagon is "monitoring" an apparent nitric acid explosion in Ukraine's Luhansk region, which Russia blamed on Ukraine.

"We've seen the Russians claim that this was a Ukrainian attack on this. We do not believe that is true," the official said. "We do believe that the Russians are responsible, but exactly what they used when they did it, why they did it, what the damage is, we just don't have that level of detail," the official said.

The official also noted that a small number of Ukrainians currently in the U.S. for "professional military education" were pulled aside for a couple days of training on Switchblade drones, which the U.S. is sending overseas as part of its military aid, according to the official.

"Although it's not a very difficult system to operate, we took advantage of having them in the country to give them some rudimentary training on that," the official said.

-ABC News' Matt Seyler