It should be the permission of every member of NATO, and I think that Hungary and Turkey might be even more reluctant than what is left of Biden's brain.
The whole facade falls apart when one recognizes the unemployed Boris Johnson was little more than Washington's errand boy, and Ukraine is little more than a client state.
Actually, there is no such thing as a NATO army, navy, air force or marine corps. When the armed forces of a member nation volunteer to fight in a forever war, they remain the armed forces of their nation. The USAF would act in support of a NATO mission, but it would so as the USAF, not being transformed into some international force.
Article 5“The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all and consequently they agree that, if such an armed attack occurs, each of them, in exercise of the right of individual or collective self-defence recognized by Article 51 of the Charter of the United Nations, will assist the Party or Parties so attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.
Any such armed attack and all measures taken as a result thereof shall immediately be reported to the Security Council. Such measures shall be terminated when the Security Council has taken the measures necessary to restore and maintain international peace and security.”
Each nation decides for itself what action it deems necessary. There is no collective vote which binds any sovereign member nation to do anything.
https://shape.nato.int/page11283634/knowing-nato/episodes/the-power-of-natos-military
The Power of NATOThe North Atlantic Treaty Organisation (NATO) is known throughout the globe as the world's strongest and most powerful Alliance; but where does NATO's power come from? Does the organisation have its own military forces or NATO troops? Simply put, no and yes. The Alliance counts on the military might of its 30 Allied and partner nations to support missions and operations around the world. NATO doesn't have its own armed forces, but it has a permanent, integrated military command structure, comprised of both military and civilian personnel, from all member states. These staffs work collectively to achieve the same objectives.
While we may not have a NATO military, the Alliance benefits from being able to count on the military capabilities and expertise of each member country. Every nation brings something to the table including personnel, but also tanks, submarines even fighter jets.
One NATO member being attacked does not require any other member to commit boots on the ground support in defense of the attacked member. Each NATO member decides for itself what action it deems necessary.
It is useful in the case of alleged war crimes, for example the bombing of the former Yugoslavia. Approval for such action failed in the UN Security Council. The NATO members did not do it, it was a collective NATO operation. NATO did not do it, they have no armed forces. Life is grand.
Think of it like the military orders to take the Swine Flu shot. The order came from the Executive Officer. If, as a side effect, you were crippled, the XO was not responsible; all he did was give an order based on the best medical advice available to him. The Medical Officer was not responsible; he did not order anyone to do anything. All he did was render his best medical opinion. The buck ends nowhere.