Originally Published: 15 JUN 22 11:14 ET

Updated: 15 JUN 22 13:08 ET

By Barbara Starr and Jeremy Herb, CNN

(CNN) -- The Biden administration announced on Wednesday it was providing an additional $1 billion in military aid to Ukraine to fight Russia, a package that includes shipments of additional howitzers, ammunition and coastal defense systems.

US President Joe Biden spoke by phone with Ukrainian President Volodymyr Zelensky on Wednesday ahead of the announcement. According to a US official, the latest package includes 18 howitzers, 36,000 rounds of howitzer ammunition and two Harpoon coastal defense systems.

"I informed President Zelenskyy that the United States is providing another $1 billion in security assistance for Ukraine, including additional artillery and coastal defense weapons, as well as ammunition for the artillery and advanced rocket systems that the Ukrainians need to support their defensive operations in the Donbas," Biden said in a statement after the call. "We also discussed Secretary Austin's efforts in Brussels today to coordinate additional international support for the Ukrainian armed forces."

Speaking in Brussels, Defense Secretary Lloyd Austin said the US and Ukraine are "working in lockstep to meet Ukraine's requests for new capabilities, especially its need for long-range fires, armor and coastal defense."

The latest weapons package comes as Ukraine's military is burning through its Soviet-era ammunition, while Ukrainian officials have pleaded with the West to send additional heavy weaponry as the war with Russia girds on. Western intelligence and military officials believe the war is at a critical stage that could determine the long-term outcome of the conflict, while Russia has amassed a significant artillery advantage around two key cities in eastern Ukraine.

The package is expected to include weapons and supplies that can be quickly shipped from existing US stockpiles as well as issuing new contracts for long term supplies for Ukraine.

The US will also provide $225 million in humanitarian assistance to Ukraine, which Biden said will go toward "supplying safe drinking water, critical medical supplies and health care, food, shelter, and cash for families to purchase essential items."

Austin is meeting in Brussels Wednesday with a working group of nearly 50 countries to discuss the crisis.

The US has sent a number of weapons shipments to Ukraine since Russia invaded the country in February, increasing the capabilities that it's provided to Ukraine's military as the conflict has continued. Ukrainian officials, however, have been pushing for more heavy weaponry and have expressed frustrations that munitions appear to be trickling into the fight piecemeal.

Ukraine's Deputy Defense Minister Hanna Maliar said Tuesday that the country has only received 10% of the military assistance Kyiv has requested from the West.

"Whatever efforts we put, no matter how professional our army is, without the assistance of our Western partners Ukraine will not be able to win this war," Mailar said.

This story has been updated with additional details.