I would almost never use it with an indefinite article (it is knowm as an "uncountable noun"). Obciously most Italian uses of "intervento" are something different in English like a surgical operation in hospital. However, the word comes into its prime in English with "government intervention" and especially with economics as the contrary to "laissez faire" economics. It is seen by the latter school as interference, which taken to extremes becomes communism.
mic interventionism - Wikipedia, the free encyclopedia
Advocates of free market or laissez-faire economics tend to see government intervention in the economy as harmful, due the fallacy of central planning, ...
en.wikipedia.org/wiki/Economic_interventionism - Cached - Similar
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