WASHINGTON (NewsNation) — President Joe Biden announced Thursday plans to send an additional $800 million in military aid to help Ukraine fight back against the Russian invasion.

“Our unity at home and in Ukraine is sending an unmistakable message to Putin,” Biden said. “He will never succeed in dominating all of Ukraine.”

The new military assistance package includes much-needed heavy artillery, 144,000 rounds of ammunition and drones for Ukrainian forces in the escalating battle for the Donbas region of eastern Ukraine. It builds on roughly $2.6 billion in military assistance that Biden had previously approved for Ukraine.

Biden said that the $13.6 billion approved last month by Congress for military and humanitarian assistance was “almost exhausted.” He said the new aid package is going “directly to the front lines of freedom” in order to “beat back Putin’s savagery.”

The aid includes additional howitzers and artillery rounds and Phoenix Ghost drones — a weapon the Pentagon said is “designed to deliver a punch.” The drone was custom-made by the Air Force to use against the Russians.

In addition to the military package, Biden announced a new program to expedite the arrival of Ukrainian refugees. Under the Homeland Security Department program, “Uniting for Ukraine,” Americans and groups, including nonprofit organizations and churches, can apply to sponsor displaced Ukrainian citizens. The application site will go live April 25.

To be eligible, Ukrainians must have been living in Ukraine on Feb. 11, must have a U.S. sponsor and must meet public health standards, including vaccination requirements. The program would provide a quick solution to the current migration crisis.

Biden said the U.S. would not lessen its resolve.

“This is our responsibility,” Biden said as he announced $500 million in direct economic assistance to the Ukrainian government to help stabilize the economy, support shelled communities and pay first responders.

The new aid package comes as the war stretches into its third month and as Russian forces began a new full-scale offensive to take control of eastern Ukraine this week.

On Wednesday, Biden lauded U.S. military officials for “exceptional” work arming Ukraine as he gathered the nation’s military brass for their first in-person group meeting at the White House of his presidency.

It’s an annual tradition that had been put on hold because of the coronavirus pandemic but is now being resurrected as the U.S. arms Ukraine to help it fight back against Russia’s invasion.

“I don’t know about you, but I’ve been to Ukraine a number of times before the war … and I knew they were tough and proud but I tell you what: They’re tougher and more proud than I thought,” Biden told military commanders. “I’m amazed at what they’re doing with your help.”

Russian President Vladimir Putin ordered his forces not to storm the last remaining Ukrainian stronghold in the city of Mariupol on Thursday but instead to blockade it so tightly “that not even a fly comes through.”

However, leaving the plant in Ukrainian hands robs the Russians of the ability to declare complete victory in Mariupol, which has seen some of the most dramatic fighting of the war and whose capture has both strategic and symbolic importance.

Biden’s remarks come as a new NewsNation/Decision Desk HQ poll found that 37.6% of Americans strongly disprove of Biden. About 24 percent strongly approve. The poll also found that nearly 43 percent of those surveyed thought Russia was the biggest threat to the United States compared to other countries including China and North Korea.

You can read the full poll results here.

This story is developing. Refresh for updates.

The Associated Press contributed to this report.