The possibility of Warsaw downing Russian missiles heading toward Poland through Ukraine was laid out in June in a signed Polish-Ukrainian security agreement.
For anyone wondering why Biden would need to approve this, here’s an excerpt from the article:
While Polish Foreign Minister Radoslaw Sikorski said at the time that the matter was still under discussion, Defense Minister Wladyslaw Kosiniak-Kamysz explained that a decision by all of NATO’s member states would be necessary to take this step.
For anyone wondering why Biden would need to approve this, here’s an excerpt from the article: