A Dutch court on Wednesday sentenced two climate activists to two months in jail, one of them suspended, for targeting Johannes Vermeer's Girl with a Pearl Earring, news agency ANP said.

Three men in their forties from neighboring Belgium were arrested last week after the attack on the 1665 painting at the city's Mauritshuis museum to raise awareness about the future of the planet.

Two activists glued themselves to the painting and adjoining wall, while another nearby poured what appeared to be tomato sauce out of a tin can.

The museum said the work—which has inspired a best-selling novel and a Hollywood movie—was undamaged and went back on display the next day.

But a court in The Hague said the frame and surrounding part of the wall were harmed in what many people thought to be a "shocking" action, ANP reported.

"Anyone can imagine the fragility of such a painting and the fact that it could have been lost if it hadn't worked out," ANP quoted one judge as saying.

Prosecutors had originally requested both men be jailed for four months.

Wouter M., accused of gluing his head to the glass frame protecting the artwork, claimed he had thoroughly researched the risks of doing so beforehand, ANP reported.

Pieter G. filmed the events.

A third activist, who emptied the tin can, is to go on trial on Friday, the news agency said.

The protest action against the Vermeer is just the latest in a string of such events in recent weeks.