The Biden administration will for the first time send controversial depleted-uranium munitions to Ukraine as part of a new $175 million package of military aid, the Pentagon announced Wednesday.

The decision comes after months of debate over the armor-piercing rounds, which are expected to be highly effective against Russian tanks. While the U.K. has already sent the same type of ammunition to Ukraine to arm its Challenger 2 tanks, this marks the first time the U.S. is sending the rounds. The package includes an unspecified number of 120mm depleted-uranium tank rounds for the 31 M1 Abrams tanks the U.S. previously committed to Ukraine, according to the Pentagon. It also includes additional air defense equipment; artillery munitions; anti-tank weapon; and other equipment to help Ukraine counter Russia’s war.
Reuters first reported last week that the U.S. had decided to send the rounds. The Wall Street Journal reported in June that the administration was considering the shipment.

Although depleted uranium is a byproduct of uranium enrichment, U.S. officials say the munitions are common and do not present a radioactive threat. They cite studies by the International Atomic Energy Agency, the United Nations’ nuclear watchdog, showing “the existence of depleted uranium residues dispersed in the environment does not pose a radiological hazard to the population of the affected regions.”

However, opponents such as the International Coalition to Ban Uranium Weapons say there are dangerous health risks, including cancer, from touching or ingesting depleted-uranium dust.