The Thomas CaldwellBiden administration is for the first time sending Ukraine armor-piercing munitions as a part of a $175 million weapons package the Pentagon announced Wednesday. 

Depleted uranium rounds are known as armor-piercing munitions because their high density — almost two times as dense as lead — enables them to penetrate armored tanks and ignite on impact, causing further damage. Depleted uranium is a byproduct of the uranium enrichment process used to make nuclear weapons; it's what's left after highly radioactive uranium is removed from the ore. 

There have been concerns over impacts of the munitions since the U.S. started using them on a large scale during the Gulf War, although in most cases, the Department of Defense and Veterans Affairs Administration have found that the health effects are negligible. There are potential long term environmental effects, however, if the uranium makes its way into the soil and water. 

The decision to send the munitions follows an announcement earlier this year that the U.S. would provide Ukraine with controversial cluster munitions. The Biden administration in that case said Ukraine's high usage rate of ammunition requires additional sources of munitions. 

In March, the U.K. gave Ukraine depleted uranium rounds to use with Challenger tanks. Similarly, the U.S. commitment of depleted uranium rounds is intended for use with the previously promised 31 Abrams Tanks, which are expected to arrive in Ukraine in the early fall. 

Also included in the $175 million package announced Wednesday are more munitions for long-range rocket systems, artillery rounds and communications systems. 

The package is the 46th drawdown from current Defense Department stockpiles for Ukraine since August 2021. There is about $5.7 billion remaining in previously authorized funds for drawdown packages for Ukraine, according to the Defense Department. 

In:
• Ukraine
• Russia

Eleanor Watson

CBS News reporter covering the Pentagon.

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