The White House confirmed Tuesday that it has stopped the shipment of some air defense and precision guided weapons that were on track to be sent to Ukraine. Officials said the decision followed an assessment of U.S. stockpiles. Read more:

U.S. officials described details of the aid on condition of anonymity because it has not yet been announced. The aid signals an expansion by the U.S. in the kinds of advanced weaponry it will send to Ukraine to bolster the country’s air defenses against what has been an increasing barrage of Russian missile strikes.

The package, which was expected to be announced Wednesday, will include about $1 billion in weapons from Pentagon stocks and another $800 million in funding through the Ukraine Security Assistance Initiative, which funds weapons, ammunition, training and other assistance, officials said.

Zelenskyy and other Ukraine officials have pressed Western leaders to provide more advanced weapons, including the Patriots, to help their country in its war with Russia.