I don't know were you derive this from, we had held that discussion already and I will forward the respective articles again.
Article 19.
In time of war, Turkey not being belligerent, warships shall enjoy complete freedom of transit and
navigation through the Straits under the same conditions as those laid down in Article 10 to 18.
Vessels of war belonging to belligerent Powers shall not however, pass through the Straits except in
cases arising out of the application of Article 25 of the present Convention, and in cases of assistance
rendered to a State victim of aggression in virtue of a treaty of mutual assistance binding-Turkey,
concluded within the framework of the Covenant of the League of Nations, and registered and
published in accordance with the provisions of Article 18 of the Covenant.
In the exceptional cases provided for in the preceding paragraph, the limitations laid down in Article 10
to 18 of the present Convention shall not be applicable.
Notwithstanding the prohibition of passage laid down in paragraph 2 above, vessels of war belonging
to belligerent Powers, whether they are Black Sea Powers or not, which have become separated from
their bases, may return thereto.
Vessels of war belonging to belligerent Powers shall not make any capture, exercise the right of visit
and search, or carry out any hostile act in the Straits.
Article 20.
In time of war, Turkey being belligerent, the provisions of Articles 10 to 18 shall not be applicable; the
passage of warships shall be left entirely to the discretion of the Turkish Government.
Article 21.
Should Turkey consider herself to be threatened with imminent danger of war she shall have the right
to apply the provisions of Article 20 of the present Convention.
1.Turkey is
not a belligerent
2.Turkey has
not been threatened with imminent danger of war, as such they can't invoke Article 20
Article 23 (which you cited) regulates the passage of civilian aircraft - nothing else
So there is absolutely no Article within the Montreux Convention that would sanction or allow for a regulation by Turkey that bars everyone's warships at the present moment.
But Erdogan is the Turkish version of Putin - with the same war-crimes record, NATO partner or not.