WASHINGTON (Reuters), President Joe Biden will give an update about the Russian invasion in Ukraine Thursday, as he completes a new arms package to support his military.

Biden is to address Americans from the White House Roosevelt Room at 9.45 a.m. (1345 GMT) and a source familiar with the planning said he is “expected to provide an update on our efforts to support Ukraine and the assistance we are providing.”

Although the size of the new arms package is likely to be similar to that announced last week at $800million, other U.S. officials told Reuters earlier that details were still being worked on.

Biden hosted a White House annual gathering of U.S. military leadership on Wednesday. This was a significant event as the war is entering a dangerous new phase.

Biden opened the meeting by praising the strength of Ukraine’s military, and he said NATO’s unification had stunned Russian President Vladimir Putin.

Russia claims it is now in a new phase of its operations and that it will be “liberating” eastern Ukraine’s Donbas region. Allies of the West believe Russia will continue its campaign for many months. It could also grind to a halt and put Ukrainian fighters under pressure.

Russia claims it started a special military operation on February 24th to “denazify and demilitarize” Ukraine. That is a fake pretext, Kyiv says and Western allies deny.

The U.S. is not involved in fighting in Ukraine, but they are engaged indirectly, funding, arming and training its forces.

U.S. assistance to Kyiv last week was expanded to include artillery systems and artillery rounds as well as unmanned coast defense boats.

This week’s package of aid would be the largest U.S. military assistance to Ukraine since Russia invaded. It will cost well more than $3 billion.

Biden announced that he will fly to the Pacific Northwest for a two-day promotion of his domestic agenda.