George Clooney is marking Thursday's 60th anniversary of U.N. peacekeeping with a public service announcement praising the soldiers who wear the distinctive blue helmets.

Clooney was named a U.N. Messenger of Peace in January by Secretary-General Ban Ki-moon with a special focus on U.N. peacekeeping. He has been actively campaigning to end the five-year conflict in Darfur and traveled to visit peacekeepers in Sudan soon after his appointment.

In the spot entitled "Peace is Hard," Clooney reminds viewers that some 100,000 U.N. peacekeepers protect civilians, oversee elections and disarm ex-combatants to ensure peace in many dangerous and politically volatile regions from Congo and Liberia to Haiti and Lebanon.

"We owe all of the United Nations peacekeepers a debt of gratitude for the dangerous work they do to ensure that peace is preserved, civilians are protected and elections are respected," Clooney says in the announcement.

In 2002, the U.N. General Assembly designated May 29 as the International Day of United Nations Peacekeepers, to pay tribute and to honor the memory of the 2,400 men and women who have died on U.N. missions.

The organizations that commissioned the spot, including media mogul Ted Turner's Better World Campaign, said they expect the public service announcement to reach a global audience through YouTube, Facebook, MySpace, ThinkMTV and a variety of online and social networking portals.

Click here to watch the PSA "Peace is Hard" on YouTube.

Click here for the official website of United Nations Peacekeeping.