The tanker, known as the Skipper (formerly the Adisa), was seized because it had been previously sanctioned by the U.S. in 2022 for its involvement in an illicit oil shipping network.
The sanctions were specifically imposed because the network was accused of:
Smuggling Iranian oil: The network used a "shadow fleet" of tankers to smuggle crude oil on behalf of Iran.

G say above.

ayooo  what rule s  you follow. 

if kena sanction  usually means  ANY country  who support this sanction will/can  seize  this ship  in the port s, in int waters  etc...

example Putin , Netahyu    got ICC  sanctions  ,  they  can  catch him  in any countries  that support  ICC

US sanctions are  the strongest .
if a person get  sanction by US  ...  all  banks worldwide will  freeze  your  bank account . you need carry cash 

Gulf of America, it belongs to America so not hijacking. Just seizing properties which illegally trespass.