Biden accused Russian President Vladimir Putin’s forces of committing “atrocities” and attacking civilian areas, contrary to the Kremlin’s denials. Hours earlier, Russian forces bombed a theater in Mariupol sheltering hundreds of civilians, according to the city council there.

“Putin is afflicting appalling, appalling devastation and horror on Ukraine,” Biden said Wednesday at the White House. “It’s god awful.”

Biden said fresh US aid to Ukraine would include assistance obtaining a longer-range anti-aircraft system. Other supplies will include 800 Stinger anti-aircraft missiles, 9,000 anti-tank missiles and 7,000 small arms along with 20 million rounds of ammunition, according to a White House statement.

Together with the drones, Biden said the package demonstrates the US “commitment to sending our most cutting-edge systems to Ukraine for its defence”. He said US weapons already provided to Ukraine have helped “inflict dramatic losses on Russian forces”.

The White House statement described the drones as “100 tactical unmanned aerial systems”. The drones will be small, light single-use weapons called “Switchblades” that can be deployed by infantry, according to two people familiar with the matter – not larger aircraft that fire anti-tank missiles, such as US Predator and Reaper drones.

Biden’s remarks followed an emotional appeal from Ukrainian President Volodymyr Zelensky to Congress earlier Wednesday, in which he urged the US to close its ports to all Russian goods and provide Ukraine with fighter jets, something the Biden administration has not yet agreed to facilitate. After showing lawmakers a graphic video of Ukrainian casualties in the war, including children, Zelensky addressed Biden directly in English: “Being the leader of the world means to be the leader of peace.”

Biden called Zelensky’s speech “convincing” and said the Ukrainians have shown “remarkable courage” as they resist the Russian invasion.

The White House is touting $1-billion in security assistance the US has authorired for Ukraine in the past week, bringing the total for the last year to $2-billion. Officials note that the US is the largest donor of such aid to Ukraine.

Biden on Tuesday signed a $1.5-trillion government funding bill, and on Wednesday authorised spending $800-million on security assistance. On Saturday, he signed off an additional $200-million for arms and equipment as part of a stopgap spending bill.

Still, the assistance falls short of Zelensky’s biggest requests – a no-fly zone over Ukraine or the transfer of fighter jets from Nato countries – neither of which the White House has agreed to.

Zelensky on Wednesday urged lawmakers to remember the bombing of Pearl Harbor and the September 11 2001, terrorist attacks in New York and Washington as it weighs more aid.

“Russia has turned the Ukrainian sky into a source of death for thousands of people,” Zelensky said following a standing ovation from lawmakers.

The Ukrainian leader, who at first spoke through an interpreter and then later switched to English, continued his calls for a no-fly zone over his country but added, “If this is too much to ask, we offer an alternative,” stressing that the country needs more air defence systems like the S-300.

The previous US assistance included about 600 Stinger antiaircraft systems, 2,600 Javelin anti-armour systems, an undisclosed number of helicopters and patrol boats, 200 machine guns, 200 grenade launchers, and 40 million rounds of small-arms ammunition, Biden officials said.

The White House also is stressing what it is willing to do diplomatically and on a humanitarian basis to demonstrate support for Ukraine, announcing Tuesday that Biden will fly to Brussels next week for “extraordinary summit” with Nato allies. And he held an event Tuesday – with a crowd of reporters watching – to sign into law the government spending bill that includes a total of $13.6-billion in humanitarian, economic and defence aid for Ukraine.

(With assistance from Tony Capaccio and Jordan Fabian.)