Various theories have been proposed for the U.S. to rejoin the Open Skies Treaty without presenting it again to the Senate for advice and consent to ratification; some are legally unsupportable, while others are impractical because of institutional considerations that will likely prove insurmountable.
Latest in Senate advice and consent
BYU law professor Eric Talbot Jensen has a new article posted to SSRN (appearing in Brigham Young University Law Review) titled, "Presidential Pronouncements of Customary International Law as an Alternative to the Senate's Advice and Consent." Very interesting and well worth reading. Abstract (31 pp. pdf):