United Nations ? The world’s first permanent war crimes tribunal got the necessary international backing Thursday to come into force on July 1, a milestone hailed by human rights advocates and many nations but strongly opposed by the United States.

A dream ever since the United Nations was established more than five decades ago, the court became a reality when its founding treaty received the required 60 ratifications.

At a brief ceremony at U.N. headquarters, more than 500 supporters of the tribunal rose in a standing ovation after 10 nations deposited their ratifications, bringing the number of countries now legally bound to cooperate with the International Criminal Court to 66.

“The time is at last coming when humanity no longer has to bear impotent witness to the worst atrocities, because those tempted to commit such crimes will know that justice awaits them,” U.N. Secretary-General Kofi Annan said in a video message from Rome, where the treaty was adopted in 1998. “Let it be a deterrent to the wicked, and a ray of hope for the innocent and helpless.”

Those hopes were echoed by France, Sweden, Denmark and the Coalition for the International Criminal Court, which represents some 1,000 organizations.

“It will be the court where the Saddam Husseins, Pol Pots and Agosto Pinochets of the future are held to account,” said Richard Dicker, director of the International Justice Program at Human Rights Watch, referring to Iraq’s president, Cambodia’s late Khmer Rouge leader, and the former Chilean dictator.

Even though then-U.S. President Bill Clinton signed the Rome treaty, the U.S. seat in the crowded chamber was empty. The Bush administration boycotted the ceremony, just as it has not attended plenary meetings preparing for the court’s operations.

Pierre-Richard Prosper, the U.S. ambassador for war crimes, restated President Bush’s opposition to the treaty and refusal to ratify it. The United States fears American citizens would be subject to frivolous or politically motivated prosecutions. It is the only vocal opponent of the court.

The court will fill a gap in the international justice system first recognized by the U.N. General Assembly in 1948 after the Nuremberg and Tokyo trials for World War II’s war criminals.

At present, the International Court of Justice deals with disputes between states. Tribunals have been created for special situations, like war crimes, but no mechanism existed to hold individuals criminally responsible.