  Fifteen orbital clusters (associations) were identified among ~20000 near
Earth asteroids (NEAs). All associations were found with a high statistical
reliability using a single linkage cluster analysis algorithm and three orbital
similarity functions. The identified groups constitute a small fraction (4.74
%) of the entire sample. Nonetheless they may be hazardous to the Earth and its
inhabitants. As it happens with meteoroid streams, every year the Earth comes
very close to the orbits of each association. In two cases (2008TC3 and
2017FU102) the distance between the asteroid's and the Earth's orbits was
smaller than our planet's radius. Among the members of the identified
associations we found 331 objects larger than the Chelyabinsk asteroid and all
of them approach the Earth's orbit at a distance smaller than 0.05 [au]. Two of
the identified groups (4179) Toutatis and (251430) Itokawa support catastrophic
origins of Toutatis and Itokawa asteroids. This study does not focus on the
origin of the NEA associations, but on tracing them. Regardless of their
origin, the identified groups pose a serious threat to the Earth. Hence, to
facilitate their monitoring of we calculated coordinates of the theoretical
radiants and calendar dates of their potential activity.
