The rest of the work in the exhibition has since been placed behind protective screens, according to The Washington Post. Leporskaya's painting is undergoing restoration, which is expected to cost around $3,400.

"The ink has slightly penetrated into the paint layer since the titanium white used to paint the faces is not covered with author’s varnish, as is often the case in abstract painting of that time," Ivan Petrov wrote in Russia's Art Newspaper.

"Fortunately, the vandal drew with a pen without strong pressure, and therefore the relief of the strokes as a whole was not disturbed. The left figure also had a small crumble of the paint layer up to the underlying layer on the face."

Featured image credit: Sally Anderson / Alamy