'reciprocal assistance' is correct and can be used in written English.
You can use it when talking about two parties helping each other, providing mutual aid. For example, "The two countries signed a treaty to ensure reciprocal assistance during times of crisis".
The Inter-American Reciprocal Assistance Treaty, better known as the Rio Pact, contains a clause similar to the one that NATO members invoked last week.
The pact, a rarely used Cold War relic formally known as the Inter-American Treaty of Reciprocal Assistance, could provide hesitant countries with international cover for broader nonmilitary action, or even intervention, if it came to that.
In deciding whether to provide such assistance, the Commission shall consider whether (A) the requesting authority has agreed to provide reciprocal assistance in securities matters to the Commission; and (B) compliance with the request would prejudice the public interest of the United States.
Reciprocal assistance, a key component for survival of pastoral communities, is still practised in the agro-pastoralist community of KGR.
Rather, what is envisioned amounts to respect for others' lives, property, families, and political sovereignty and reciprocal assistance and cooperation among community members.
Under the Inter-American Treaty of Reciprocal Assistance (commonly known as the Rio Treaty), which the U.S. and Colombia both signed, an attack against one nation is to be considered an attack against them all.
Internally, the rural Minahasan are divided into special societies called mapalus, which provide reciprocal agricultural assistance.
The U.S. government and allies should stop sending lethal aid to rebels in Syria, while working for a reciprocal cutoff of all military assistance to the Syrian government by Russia and Iran".
In societies with deep social networks, Putnam noted, people tend to engage in reciprocal acts of service or assistance on the tacit understanding that a benefit extended by one person to another will be returned in kind in the future.
The notion of "reciprocal obligation" — that the government's role in public assistance is to help people help themselves — required that the government invest significantly in secondary programs related to transportation, child care and job training, which would help people find quality work that would enable them to eventually stop relying on the government for basic needs.
Finally, if subordinates are reproductively active then helping may be a reciprocal arrangement between dominants and subordinates, i.e., subordinates may help to raise dominants' broods in return for dominant assistance with the subordinates' own broods.
