The United States is speeding up the shipment of sophisticated NASAMS air defences to Ukraine, White House National Security Council spokesperson John Kirby said on Tuesday, after a devastating missile barrage from Russia.

U.S. President Joe Biden pledged to Ukraine President Volodomyr Zelenskiy in a phone call on Monday to support the country’s air defences as residents took cover from strikes in Kyiv.

The United States has approved sending Ukraine a total of eight National Advanced Surface-to-Air Missile Systems (NASAMS) so far, with two expected to be delivered soon and six more sent over a longer time frame.

We think that we’re on track to get those first two over there in the very near future,” Kirby said during a briefing for reporters. “We are certainly interested in expediting the delivery of NASAMS to Ukraine as soon as we can.”

The United States has provided more than $16.8 billion worth of security assistance since Russia invaded Ukraine on Feb. 24 and imposed a wide-ranging array of economic sanctions on Moscow over its actions in Ukraine.

Meanwhile, also on Tuesday, Ukraine received the first of four IRIS-T air defence systems Germany promised to supply, a German defence ministry source said, confirming a report by Der Spiegel magazine.

The delivery had taken place earlier than planned, the source added. The government did immediately respond to a request for official comment.

Russia pounded cities across Ukraine during rush hour on Monday morning, killing civilians and knocking out power and heat, in apparent revenge strikes after Russian President Vladimir Putin declared a blast on Russia’s bridge to Crimea to be a terrorist attack.