Biden assists in sending Ukraine an advanced air defense system, fulfilling one of Zelenskyy's biggest wishes

• Biden said the US is working with Slovakia to provide Ukraine with the S-300 air defense system.
• The US is providing provide Slovakia with a Patriot missile system in return for the transfer.

President Joe Biden said on Friday that there's "no time for complacency" as the US announced that it is working with NATO-ally Slovakia to provide Ukraine with an advanced air defense system, answering one of Ukrainian President Volodymyr Zelenskyy's personal requests.

"As the Russian military repositions for the next phase of this war, I have directed my Administration to continue to spare no effort to identify and provide to the Ukrainian military the advanced weapons capabilities it needs to defend its country," Biden said in a statement released by the White House.

Defense Secretary Lloyd Austin praised Slovakia's "generosity" in sending Ukraine an S-300 air defense system. He said it was a "strong testament" to the commitment Ukraine's neighbors are demonstrating as Russia continues its war. Biden said the US will provide Slovakia with an American-made Patriot missile system in return for the transfer.

"This deployment of Patriot capabilities to Slovakia aligns perfectly with our previous efforts to bolster NATO's defensive capabilities and to demonstrate our collective security requirements under Article 5 of the NATO treaty," Austin said in a statement.

Austin also said the Patriot system will be manned by American troops who will arrive "in the coming days." Austin said that their deployment did not have an end date as the US and Slovakia explore "more permanent air defense solutions."

Biden said that Zelenskyy had raised the S-300 system with him directly during their conversations. The S-300 is a Soviet-era system that can reach altitudes of up to 18 miles, The Washington Post previously reported.

"Now is no time for complacency," Biden said. "The Russian military may have failed in its objective of capturing Kyiv, but it continues to inflict horrific acts of brutality on the Ukrainian people."

In an emotional speech to Congress last month, Zelenskyy called for the US to support a no-fly zone in Ukraine. He added that if this was "too much to ask for," then Ukraine needed better anti-aircraft systems like the S-300. "Russia has turned the Ukrainian sky into a source of death for thousands of people," Zelenskyy said at the time. The US and NATO have opposed a no-fly zone because it would require the alliance to shoot down Russian warplanes. This would effectively amount to a declaration of war, and spark a direct confrontation between a number of nuclear powers.

Since launching an unprovoked war against Ukraine in late February, Russia has struggled to make major gains on the ground. The Russian military, which has lost thousands of soldiers since the war began, failed to take Kyiv. Russia is now focusing its offensive on the eastern Donbas region.

After invading Ukraine and annexing Crimea in 2014, Russia began supporting rebels in a war against Ukrainian forces in the eastern Donbas region. The conflict in the Donbas raged on for eight years before Russia began its most recent invasion of Ukraine in February. The separatists control roughly one-third of the region, and NATO believes Moscow will move to conquer the rest of the Donbas in the days to come.

NATO Secretary-General Jens Stoltenberg on Tuesday said that Russia would launch a "concentrated" offensive in the Donbas.

"In the coming weeks we expect a further Russian push in the east and southern Ukraine, to try to take the entire Donbas and to create a land bridge to the occupied Crimea," the NATO chief said.

But Stoltenberg in an interview with NPR on Friday also warned that Russian President Vladimir Putin has not "changed his overall aim, and that is to control Ukraine."