Pallets of 155 mm shells ultimately bound for Ukraine are loaded by the 436th Aerial Port Squadron, on April 29, 2022, at Dover Air Force Base, Delaware US (AP)

The United States pledged Friday to supply Ukraine with $2.1 billion in military aid in the form of a package that includes munitions for air defense systems and drones, the US Defense Department said.

"Today, the Department of Defense (DoD) announced a new security assistance package, underscoring the unwavering US support for Ukraine," the Pentagon said.

"This package, which totals up to $2.1 billion and includes critical air defense and ammunition capabilities, is being provided under the Ukraine Security Assistance Initiative (USAI)," it added.

The latest military aid package handed to Ukraine was a $300 million one back in May. Politico reported at the time that the Biden administration is predicted to announce a fresh military aid package for Ukraine on Wednesday amounting to $300 million, which includes artillery and mortar ammunition.

Citing US officials, Politico claimed that the package will include trucks, heavy equipment, and spare parts, in addition to Hydra-70 rockets, which are typically used in an air-to-ground operation mode.

The first package this year was a $3 billion package in military aid to Ukraine which included Bradley military vehicles, self-propelled Howitzer artillery guns, MRAPS vehicles, Sea Sparrow missiles, and ammo, among other military materials and equipment.

In February, the Pentagon announced a $460 million package to Ukraine which included "more ammunition for US-provided HIMARS and howitzers that Ukraine is using to defend their country as well as more Javelins, anti-armor systems, and air surveillance radars" per a Pentagon statement at the time.

During a surprise visit to Ukraine that month, US President Joe Biden expressed his country's unceasing support after taking the chance to promise Ukrainian president, Volodymyr Zelensky that more arms will be sent and that they have his unflagging commitment to helping Ukraine.

Then in March, the US announced that it will provide Ukraine with new military aid amounting to $350 million, including HIMARS and howitzers ammunition, anti-tank systems, and Bradley armored vehicles.

"Russia alone could end its war today. Until Russia does, we will stand united with Ukraine for as long as it takes," Secretary of State Antony Blinken stated at the time.

Washington specified that the package also includes munitions for Patriot air defense systems, HAWK air defense systems, and missiles, as well as Puma drones and laser-guided rocket system munitions.

The Ukraine Security Assistance Initiative authority procures the equipment from the defense industry or partners instead of drawing from Pentagon stocks, the statement explained after numerous countries ran out of munition and weapons because of giving Kiev weapons from their own stockpiles.

Ukrainian forces are reportedly using 6000 artillery shells per day. The munition stocks in the arsenals of Western arms-supplier are being steadily depleted, US newspaper The Week reported in late March.

Polish and EU officials are negotiating a military rejuvenation program worth $2.2 billion for the sake of maintaining a steady supply of arms for Ukraine "and to replenish Europe's dwindling stocks", the Associated Press reported.

The US was also reportedly suffering from a critical shortage in military supplies. Seth Jones of the Center for Strategic and International Studies (CSIS) assesses the munition stockpiles that the US has been export-funneling to Ukraine have steadily decreased since the outbreak of the war.

Back in December, researchers of the Foreign Policy Research Institute argued that "Ammunition availability might be the single most important factor that determines the course of the war in 2023, and that will depend on foreign stockpiles and production."

The US has been one of the most steadfast supporters of Kiev since the outbreak of the war with Russia. In May 2022, the US Senate approved a $40 billion Ukraine supplies package, including more than $20 billion in military funding. Additionally, back in February, the US announced its intentions to dedicate $9.9 billion of its budget in support of Ukraine.

Now, in light of the reported audacious change in the US strategy, the threshold for escalation will be raised significantly.