United States President Joe Biden leaves for Brussels on Wednesday for meetings with European leaders regarding Russia's invasion of Ukraine, bringing with him preparations for more penalties against Moscow, sources said.

According to two persons familiar with the matter, Biden and his team were working on plans to censure members of Russia's parliament, the Duma, in response for Russia's invasion of Ukraine.

Biden departs from the White House at 8:40 a.m. EDT on a journey that will include meetings with NATO and European Union leaders in Brussels and a visit to Warsaw for consultations with Polish President Andrzej Duda.

Thursday is likely to see the announcement of the sanctions.

In a report by the Wall Street Journal, it said some 300 Duma members could face sanctions.

Additionally, the White House said that Biden will conduct a teleconference Monday with Germany's Olaf Scholz, France's Emmanuel Macron, Italy's Mario Draghi, and the United Kingdom's Boris Johnson to discuss their synchronized reactions to Russia's invasion of Ukraine.

A White House official said "no final decisions have been made regarding who will be sanctioned or how many will be sanctioned."

According to White House national security adviser Jake Sullivan, Biden will attend an emergency NATO meeting on Thursday, meet with Group of Seven (G7) leaders, and address the European Union's 27 leaders at a European Council session.

"We will announce more sanctions measures on Thursday, when the president meets with our partners," a White House representative said.

Sullivan said Biden will oversee the next step of military support to Ukraine.

Along with new sanctions on Russia, Biden would engage with US allies to tighten existing penalties in order to "curb evasion and assure robust enforcement," Sullivan said.

Biden has sworn not to engage in direct combat with Russia but to defend all NATO territories. 

He has directed that additional US soldiers be deployed to NATO's eastern flank in order to reassure those nervous partners.

Biden will visit US troops in Poland and speak with humanitarian professionals working to assist hundreds of thousands of Ukrainians who have fled their nation and those who remain.

Last week, US Defense Secretary Lloyd Austin and his colleagues deliberated on how to defend the organization's eastern flank, which stretches from Estonia in the north through Latvia, Lithuania, and Poland in the east and Bulgaria and Romania on the Black Sea in the west.