The White House is expected to announce as soon as Thursday another assistance package for Ukraine that will include more High Mobility Artillery Rocket Systems (HIMARS) and more ammunition for the U.S.-provided Howitzers, according to U.S. officials.
The four HIMARS the U.S. announced in a previous aid package have arrived in Ukraine but have not yet been used.
In the battle in eastern Ukraine, the Ukrainians have been outgunned by the Russians. The U.S. first sent Howitzers and have since started sending the longer-range and more accurate HIMARS to enhance Ukrainian firepower.
In announcing the first shipment that included HIMARS, Under Secretary of Defense for Policy Dr. Colin Kahl said, "The HIMARS, and the guided munitions that go along with them will allow Ukraine to range any target they need for that fight inside Ukrainian territory."
Ukrainian leaders assured the U.S. that the systems would not be used to strike into Russia.
The munitions sent by the U.S. with the first shipment of HIMARS have a range of up to 70 kilometers, more than twice the range of M777 Howitzers, but less than the long-range Advanced Tactical Missile Systems (ATACMS) that can reach hundreds of kilometers.
"We don't assess that they need systems that range out hundreds and hundreds of kilometers for the current fight, and so that's how we settled on it," Kahl said earlier this month.
Since Ukrainian forces don't use HIMARS, the U.S. organized training that takes about three weeks for Ukrainians outside of Ukraine. The U.S. prepositioned the four HIMARS in Europe so training could start quickly, and the first 60 Ukrainians graduated from training last week.
The HIMARS are a priority for Ukraine which is losing 100 soldiers a day. The HIMARS provide more precision-guided targeting with extended range so the Ukrainians can hit high-valued Russian targets from farther away.
Russia is also taking significant losses despite its numerical superiority. The Russian Defense Ministry hasn't given estimated casualties for months, but Chairman of the Joint Chiefs of Staff General Mark Milley said last week that Russia has lost between 20-30% of its armored forces and has "suffered a tremendous amount of casualties."
The fight in the east has been described as a street-by-street battle that could take months, if not years. The U.S. has provided more than $5.6 billion in security assistance to Ukraine since Russia invaded Ukraine. Congress recently approved a $40 billion security package for Ukraine that will allow for more aid shipments through the summer.
David Martin is CBS News' National Security Correspondent.
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