This is the 4409th most frequent Russian word.
взаимного
Mutual.
The word 'взаимного' is an adjective used to describe 'доверия' (trust), emphasizing its reciprocal nature in the relationship.
Мы стремимся к установлению взаимного доверия.
We strive to establish mutual trust.
Here, 'взаимного' qualifies 'уважения' (respect), highlighting the bidirectional aspect of the respect in their friendship.
Их дружба основана на принципе взаимного уважения.
Their friendship is based on the principle of mutual respect.
Used as an attribute for 'сотрудничества' (cooperation), 'взаимного' stresses the mutual and shared involvement in the cooperation.