President Biden on Thursday announced a "new humanitarian parole program" to welcome Ukrainian citizens fleeing Russia's unprovoked invasion into the U.S.

The big picture: The program — known as "Uniting for Ukraine" — is part of the Biden administration's commitment to welcome up to 100,000 Ukrainians and others fleeing the war.

• Senior Homeland Security and National Security Council officials told reporters earlier on Thursday that they anticipate that the majority of the 100,000 will enter the U.S. via this effort.

State of play: The U.S. is strongly encouraging Ukrainians who do not have a visa or are not eligible for one to seek entry into the U.S. via "Uniting for Ukraine," which will allow Ukrainian citizens to apply for humanitarian parole.

• Senior DHS and NSC officials said that the program "is a clear expression of solidarity" with displaced Ukrainians.

Details: To be eligible for the program, Ukrainians must have been living in Ukraine as of Feb. 11, have a sponsor in the U.S., complete vaccinations and other public health requirements and pass "rigorous" screenings and security checks, per a DHS press release.

• A DHS website will go live on April 25 for U.S. individuals to apply to become sponsors. They must commit to providing financial and other types of support for the people they sponsor.
• Senior DHS and NSC officials said they are working with "outside organizations" to facilitate matching sponsors with Ukrainian nationals who do not have any U.S. ties.
• There is no limit on the number of individuals a person can sponsor. Officials expect that most applicants will be family units.

Yes, but: Starting on April 25, Ukrainians who have traveled to Mexico seeking to come into the U.S. will be denied entry in order to discourage travel from refugees to that country.

• This is a reversal from the previous memo issued by DHS instructing border officials to consider using exemptions for Ukrainians rather than sending them to Mexico under a COVID-linked policy known as Title 42.
• "We will apply Title 42 equally to all nationalities at the border, and Ukrainian nationals who present and do not have a visa or have not gone through the 'Uniting for Ukraine' program will no longer be paroled in," senior DHS and NSC officials said.

What he's saying: "This new humanitarian parole program will complement the existing legal pathways available to Ukrainians, including immigrant visas and refugee processing," Biden said.

• "It will provide an expedient channel for secure legal immigration from Europe to the United States for Ukrainians who have a U.S. sponsor, such as a family or an NGO."
• "This program will be fast, it will be streamlined, and I'm sure the United States will honor its commitment to the people of Ukraine," adding that they "need not go through our Southern border."

What's also happening: The State Department will provide more resources to process Ukrainian citizens for refugees resettlement.

• Additionally, the department said it will work with European partners, the UN High Commissioner for Refugees and nongovernmental organizations to identify "particularly vulnerable" Ukrainians and others fleeing the war who may warrant permanent resettlement through the U.S. Refugee Admissions Program.
• Those deemed "particularly vulnerable" include women and girls, children, older people, LGBTQ individuals, disabled people and people of color, per a press release.

"We are proud to deliver on President Biden’s commitment to welcome 100,000 Ukrainians and others fleeing Russian aggression to the United States. The Ukrainian people continue to suffer immense tragedy and loss as a result of Putin’s unprovoked and unjustified attack on their country," Homeland Security Secretary Alejandro Mayorkas said in a statement.

• "We will help deliver on the President’s commitment to welcome 100,000 Ukrainian citizens and others forced to flee their homes in Ukraine, and our partnership with the Department of Homeland Security will help us fulfill that commitment," said Secretary of State Antony Blinken.

Go deeper:

• Axios explains Ukraine
• The latest on the Russia-Ukraine crisis