Following an overlong and inexplicable delay since his powerful speech at the United States Holocaust Memorial Museum in early April, President Bush has announced an increased sanctions package against Sudan in an attempt to halt the ongoing slaughter of Darfurians by government-backed militias. The announcement is a major step in fulfilling America's leadership role in addressing the genocide and inspiring other international actors to do their part.

The new sanctions target companies owned or controlled by the Sudanese government, as well as individuals seen as contributing to the slaughter. The president imposed an expanded embargo on arms sales to Sudan. And he ordered consultations with Britain and other allies on a UN Security Council resolution endorsing such sanctions.

Since the crisis in Darfur erupted in 2003, janjaweed militias backed by the Sudanese government have been responsible for the deaths of hundreds of thousands of civilians and the exile of perhaps millions more in their efforts to suppress rebel groups. The Sudanese government continues to obstruct the deployment of UN peacekeepers, and in perhaps its most blatant and obscene act yet, sent in arms shipments in airplanes painted to resemble international aid transports.

Whether the implementation of what is known as "Plan B' will have any effect on Khartoum, which continues to thumb its nose at international opinion, or China, which covets Sudanese oil, is an open question. What's clear is that nothing will happen without the United States taking the lead. The United States must now turn its sights on the United Nations and let the world body know in no uncertain terms that its credibility rests on adopting an identical program of embargoes and sanctions and a ban on Sudanese military flights over Darfur.