A senior defense official has been cited as saying the specific weapons will be tailored to repel a broader Russian assault in the Donbas, though the recent weeks of fighting have made clear that battlefield momentum is currently with the Russians.

"Heavy artillery platforms, like howitzers and High Mobility Artillery Rocket Systems, or HIMARS, sit high on Ukrainian military wish lists," CNBC writes, citing the source. "The official said the latest security package will include four additional HIMARS, which brings the total number of HIMARS transfers to Ukraine from U.S. arsenals to 12."

The total in US military and humanitarian aid so more is more than $7 billion given since February.

The longer-range HIMARS are being sought by the Zelensky government as potentially game-changing given they allow the Ukrainians for the first time to strike Russian military stockpiles and command centers that extend deeper behind enemy lines. 

Axios details of some of the major US-supplied currently operational in eastern Ukraine after the several rounds of weapons systems were transferred, and as Ukrainian troops get trained on them: