The NATO treaty calls for mutual defense.
The immediate realization of Articles 5 and 6 of the NATO treaty will stay untouched by this from the start.
The NATO treaty was drawn up, and signed by the U.S., to protect Western Europe against the Soviet Union.
NATO treaties obliged the U.S. government to pay 75% of this compensation, which it did.
In such a war, the U.s. military and our financial institutions would be obliged by NATO treaty to support Turkey.
Although the NATO treaty did not cover colonies, Portugal insisted that its overseas interests were not colonies but an integral part of the Nation of Portugal.
That flies in the face of the open-door policy in the original NATO treaty and effectively slams that door in the face of the Baltic states.
The attacks of 11 September 2001, triggered Article 5 of the NATO treaty, stating that an attack against any member would be regarded as a direct attack on all parties.
Note that before the attackers in the September 11, 2001 attacks were identified, the US invoked the NATO treaty, without objection, as a member state that had been attacked.
Turkey two days ago invoked Article IV of the NATO treaty, which obligates all members to consult if any of them declares itself at risk of attack.