DUBAI, United Arab Emirates — Iran’s supreme leader said Thursday that the only place Americans belonged in the Persian Gulf is “at the bottom of its waters” and that a “new chapter” was being written in the region’s history.

Ayatollah Mojtaba Khamenei, speaking in a written statement read by a state television anchor as he has since taken over as Iran’s supreme leader, struck a defiant tone, insisting that the Islamic Republic will protect its “nuclear and missile capabilities” as a national asset, likely seeking to draw a hard line as US President Donald Trump seeks a wider deal to cement the shaky ceasefire now holding in the war.

Khamenei was reportedly badly wounded in the February 28 attack that killed his father, the 86-year-old Supreme Leader Ayatollah Ali Khamenei, and he has not been seen in public or on video since he assumed his father’s role as supreme leader in March.…