  Near-Earth asteroids (NEAs) that may evolve into impactors deserve detailed
threat assessment studies. Early physical characterization of a would-be
impactor may help in optimizing impact mitigation plans. We first detected NEA
2023~DZ$_{2}$ on 27--February--2023. After that, it was found to have a Minimum
Orbit Intersection Distance (MOID) with Earth of 0.00005~au as well as an
unusually high initial probability of becoming a near-term (in 2026) impactor.
We aim to perform a rapid but consistent dynamical and physical
characterization of 2023~DZ$_{2}$ as an example of a key response to mitigate
the consequences of a potential impact. We use a multi-pronged approach,
drawing from various methods (observational/computational) and techniques
(spectroscopy/photometry from multiple instruments), and bringing the data
together to perform a rapid and robust threat assessment.} The visible
reflectance spectrum of 2023~DZ$_{2}$ is consistent with that of an X-type
asteroid. Light curves of this object obtained on two different nights give a
rotation period $P$=6.2743$\pm$0.0005 min with an amplitude
$A$=0.57$\pm$0.14~mag. We confirm that although its MOID is among the smallest
known, 2023~DZ$_{2}$ will not impact Earth in the foreseeable future as a
result of secular near-resonant behaviour. Our investigation shows that
coordinated observation and interpretation of disparate data provides a robust
approach from discovery to threat assessment when a virtual impactor is
identified. We prove that critical information can be obtained within a few
days after the announcement of the potential impactor.
