a treaty
... that in 2019, the United States ratified a treaty that had been negotiated 16 years earlier to protect the wreck of the RMS Titanic?
... that in 2019, the United States ratified <b id="mwAfk"><a href="./Agreement_Concerning_the_Shipwrecked_Vessel_RMS_Titanic" id="mwAfo" rel="mw:WikiLink" title="Agreement Concerning the Shipwrecked Vessel RMS Titanic">a treaty</a></b> that had been negotiated 16<span id="mwAfs" typeof="mw:Entity"> </span>years earlier to protect the <a class="mw-redirect" href="./Wreck_of_the_RMS_Titanic" id="mwAfw" rel="mw:WikiLink" title="Wreck of the RMS Titanic">wreck of the RMS<span id="mwAf0" typeof="mw:Entity"> </span><i id="mwAf4">Titanic</i></a>?