"Well certainly it is not a question of lack of will," Austin said on Wednesday, when asked whether the reason for limited supplies lies in the lack of will or the lack of necessary weapons.
The British broadcaster Sky News reported on Thursday, citing a senior diplomat, that the shortage of air defense systems was the key factor limiting the ability of Western countries to meet to Ukraine’s weapon needs.
NATO Secretary General Jens Stoltenberg said prior to the sixth Ukraine Defense Contact Group meeting in Brussels on Wednesday, that the focus of arms deliveries to Ukraine will now shift to air defense systems.
On February 24, Russia began a military operation in Ukraine responding to calls for help from the breakaway republics of Donetsk and Luhansk. Western countries responded by imposing comprehensive sanctions against Moscow while also ramping up their military support for Kiev.
In April, Russia sent a note to NATO member states condemning their military assistance to Ukraine. Russian Foreign Minister Sergey Lavrov warned that any arms shipments on the Ukrainian territory would be "legitimate targets" for Russian forces.