https://phys.org/news/2019-03-indian-satellite-destruction-debris-field.html

"Unfortunately, there is no binding international legal rule (yet) which prohibits the wanton creation of space debris," said Frans von der Dunk, professor of space law at the University of Nebraska-Lincoln.

At the same time, the test "strictly speaking" was a violation of the obligation under the 1967 Outer Space Treaty to inform other countries of the test "since they might well suffer harmful interference with their own satellite operations," von der Dunk said.