What does the term 'salvo' mean in the given context?
WASHINGTON (Reuters) - President Donald Trump backed boycotting American motorcycle manufacturer Harley Davidson Inc on Sunday, the latest salvo in a dispute between the company and Trump over tariffs on steel.
According to Collins dictionary, salvo can mean:
countable noun
A salvo is the firing of several guns or missiles at the same time in a battle or ceremony.
countable noun
A salvo of angry words is a lot of them spoken or written at about the same time.
It seems that the definition 2 is more close to this context, but I am not sure how to understand it in this context. Can someone help to elaborate a bit?
The full source.