U.S. military forces fire a High Mobility Artillery Rocket System (HIMARS) rocket during the annual Philippines-US live fire amphibious landing exercise (PHIBLEX) at Crow Valley in Capas, Tarlac province, north of Manila, Philippines October 10, 2016.
U.S. military forces fire a High Mobility Artillery Rocket System (HIMARS) rocket during the annual Philippines-US live fire amphibious landing exercise (PHIBLEX) at Crow Valley in Capas, Tarlac province, north of Manila, Philippines October 10, 2016. Reuters / Romeo Ranoco

The United States will send four more high mobility artillery rocket systems (HIMARS) to Ukraine, U.S. Defense Secretary Lloyd Austin said on Wednesday, in the latest military package to help it defend itself against Russian forces.

Russia's Defense Minister Sergei Shoigu earlier this week ordered generals to prioritize destroying Ukraine's long-range missiles and artillery after Western-supplied weapons were used to strike Russian supply lines.

Nearly five months since President Vladimir Putin ordered the invasion, Russian forces are grinding through the Donbas region of eastern Ukraine and occupy around a fifth of the country.

"(We) will keep finding innovative ways to sustain our long-term support for the brave men and women of the Ukrainian armed forces and we will tailor our assistance to ensure that Ukraine has the technology, the ammunition and the sheer firepower to defend itself," Austin said at the start of a virtual meeting with allies on Ukraine.

The West has supplied Ukraine with longer-range heavy artillery and multiple launch rocket systems so it can hold out despite Russian artillery supremacy in numbers and ammunition.

Ukraine says it has carried out successful strikes on 30 Russian logistics and ammunitions hubs, using several multiple launch rocket systems recently supplied by the West.

In a press conference after the meeting, Chairman of the U.S. Joint Chiefs of Staff General Mark Milley said Ukraine had used HIMARS to hit Russian command and control nodes, logistic network and air defense sites within Ukraine.

About 200 Ukrainian forces had been trained on the HIMARS and none of the systems had been destroyed by Russian forces, Milley said.

He added an issue would be the rate of ammunition being used by Ukrainian forces, though there would be no impact on the readiness of the United States in the next couple of months at the current rate.

Milley said the Donbas region had not been lost by Ukrainians yet and described it as a "grinding war of attrition."

HIMARS have a longer range and are more precise than the Soviet-era artillery that Ukraine has had in its arsenal.

Austin said the new package would also include rounds for Multiple Launch Rocket Systems as well as artillery munitions.

The latest package would bring the total number of HIMARS the United States has provided to Ukraine to 16.

The United States has provided $8 billion in security assistance since the war began, including $2.2 billion in the last month.

Russian Foreign Minister Sergei Lavrov said on Wednesday that Moscow's military "tasks" in Ukraine now went beyond the eastern Donbas region, in the clearest acknowledgment yet that it has expanded its war goals.

Austin said Lavrov's comments appeared to be aimed at the Russian population.

"That's not a surprise to any of us or anybody in Europe or anybody around the globe, I think he's talking to the people in Russia who have been ill informed throughout," Austin told reporters.

The United States and allies are starting to examine possible training for Ukrainian pilots as part of a project to help build a future Ukrainian air force, Air Force Chief of Staff General Charles "CQ" Brown told Reuters.

A number of different options were being looked at on helping Ukrainian troops, including training for pilots, but no decision had been made, Milley said.