Oct. 4 (UPI) -- The Biden administration announced an additional $625 million in military assistance for Ukraine on Tuesday that includes several advanced rocket systems, which officials say have been integral to Kyiv's defense.
President Joe Biden informed Ukrainian President Volodymyr Zelensky over the phone of the new package, stating it will include high mobility artillery rocket systems, armored vehicles and ammunition, among other lethal equipment.
Joined on the line by Vice President Kamala Harris, Biden pledged to Zelensky that the United States will "continue supporting Ukraine as it defends itself from Russian aggression for as long as it takes," according to a readout of the conversation from the White House.
The announcement of additional aid comes as Kyiv continues to reap military victories in its war against the Kremlin, despite its rubber-stamped annexation of four regions in the Ukrainian east and south following last month's referendums that the international community widely discredited as shams.
On Tuesday, Russia's upper house of parliament, known as the Federation Council, unanimously approved laws to accept the four regions of Donetsk, Lugansk, Kherson and Zaporozhye as Russian territory and those who reside within them as Russian, according to Russian state-news agency TASS.
While Russia -- which launched its invasion of Ukraine in late February -- was attempting to annex Ukrainian land via bureaucracy, the Ukrainian military was stating it continued to regain more territory than Russia was in the process of attempting to claim.
Biden told Zelensky that the United States will never recognize Russia's attempted annexation of Ukrainian territory while repeating the threat that they stand ready "to impose severe costs on any individual, entity or country that provides support to Russia's purported annexation."
Deputy Assistant Secretary of Defense Laura Cooper told reporters during a press conference Tuesday afternoon that the package for Kyiv, which is to be drawn from U.S. stockpiles, "is tailored to meet Ukraine's immediate needs," including to "maintain momentum in the east and in the south."
Within the package are four HIMARs, which will bolster the total number the United States has given Ukraine from its stockpiles to 20. Washington, D.C., has also committed an additional 18 that are to come directly from the manufacture once constructed. Allies have also provided Ukraine with 10 systems with more coming, U.S. officials said.
The ultra-mobile rocket system has been celebrated for its effect on the battlefield, with Zelensky in early August stating "the word 'HIMARS' has become almost synonymous with the word 'justice' for our country."
Cooper said that in the war, HIMARS have become "pretty famous."
"You've seen how the Ukrainians can use these capabilities to take out critical Russian logistics nodes, command and control nodes, ammunition depots, etc. And really weaken the Russian forces' ability to respond," she said.
"So, having these additional four HIMARS is going to enable the Ukrainians and the other capabilities as well to have flexibility in how they employ these capabilities with their forces as they look for additional opportunities to seize the strategic advantage," she said.
The drawdown for Ukraine is the first of the fiscal year and the 22nd since August of 2021.
Amid the Biden administration, the United States has committed more than $17.5 billion in security assistance to Ukraine, the vast majority of which was announced since Russia invaded Ukraine on Feb. 24, according to a fact sheet from the Defense Department.
Along with the four HIMARS, Tuesday's package includes 16 155mm Howitzers, 200 MAXXPro Mine Resistant Ambush Protected Vehicles, Claymore anti-personnel munitions and hundreds of thousands of ammunition rounds of various sizes.
Zelensky on Tuesday tweeted his thanks for what he described as "substantial support" for Ukraine.
"Our victories within the ongoing defense operation are a joint success of [Ukraine], [The United States] and the entire free world," he said.