saber rattling vs sabre rattling

saber rattling and sabre rattling both are nouns.

Word	Noun	Adjective	Verb	Adverb
saber rattling	Yes	No	No	No
sabre rattling	Yes	No	No	No

As nouns, saber rattling and sabre rattling are synonyms defined as:

saber rattling and sabre rattling: the ostentatious display of military power (with the implied threat that it might be used)

saber rattling (noun)	sabre rattling (noun)
the ostentatious display of military power (with the implied threat that it might be used)	the ostentatious display of military power (with the implied threat that it might be used)