The phrase "are ensured only" is correct and usable in written English.
It can be used to emphasize that something is guaranteed or secured exclusively under certain conditions or circumstances.
Example: "The benefits of the program are ensured only for those who meet the eligibility criteria."
Alternatives: "are guaranteed solely" or "are secured exclusively".
With regard to race, Obama's historical significance is ensured; only his impact and legacy are up for debate.
A safe and reliable product can be ensured only by considering probabilities or statistics in the design process.
Thus Cumberland's reply to Hobbes's egoism is that in fact the happiness of the individual is ensured only if he works for the common good.
The plane's survival was ensured only by Emirates, which uses its home in Dubai as a hub for about 1,500 flights a week.
A good dispersion of nanozeolites is ensured only when a stabilizer (polyethylene glycol (PEG) with M = 1000 g/mol) is used.
It is shown that the dynamics of an elastic cable submerged in a heavy fluid, such as water, are dominated by its elastic stiffness; hence dynamic similitude is ensured only if the elasticity of the line is properly modelled.
For such a material, contrarily to hyperelastic models, no potential can be defined, and thus the conservation of the energy is ensured only if the elastic work of deformation can be restored by the scheme.
The rationale was that the bag of atomic secrets had grown so large that protection would be ensured only if the most serious topics were set aside for stringent safeguarding.
He realized that the real threat to the country was a weak, apathetic citizenry; strength could be ensured only through promotion of nationalistic sentiment, including loyalty to the emperor as the real sovereign.
Since a WIC round can be ensured only with a correct coordinator, we need to ensure that the coordinator is eventually correct.
