"necessary response" is correct and can be used in written English.
For example, "After reviewing the situation, my necessary response was to take action immediately."
Accountability is a necessary response.
It's a rational, necessary response to the end of lifetime employment," he wrote.
What some see as a necessary response to Euroscepticism, others see as a capitulation to it.
Mrs. Rell and Democratic leaders insisted their actions were a necessary response to a potential crisis.
It's a necessary response, but, on style points, the class clown always beats the teacher's pet.
The officials added that the actions were a necessary response to "very disturbing Russian threats to US national security".
But her violence comes across as a necessary response to the brutal world into which she has fallen.
"Radical fundamentalists are waging a world war," he said, calling the United States invasion a necessary response to Islamic terrorism.
And her reasons — for defending Shiite militias as a necessary response to Sunni Arab violence, for example — are personal.
So the resolution we have just adopted is our necessary response if we are to save the people of Darfur".
Shutting down the Gitmo commissions would be an appropriate and necessary response to the Senate report's findings on torture.
