At the recently completed Review Conference of the International Criminal Court (ICC) in Kampala, Uganda provided State Parties their first formal opportunity to assess the Court’s performance to date. It was also the first chance to assess the decision by the Obama administration to attend ICC meetings, reversing the Bush administration's boycott.

Two important truths emerged. First, many parties to the ICC are more interested in using the Court to make political points than to hold those who perpetrate the worst atrocity crimes accountable. Second, there is no substitute for U.S. engagement with the Court in keeping the ICC focused on its proper mission.

Nearly eight years have passed since the ICC entered into force with jurisdiction to prosecute those who commit genocide, crimes against humanity and serious war crimes who are not prosecuted by national courts.

Now with 111 State Parties, the ICC has established itself as the presumptive forum for international trials of atrocity crimes, even charging the sitting president of Sudan Omar al-Bashir with genocide. But the ICC’s track record to date has been limited, having not completed a single trial despite opening investigations into five situations in Africa. The ICC’s difficulties can be attributed in large part to inadequate cooperation from its members in apprehending suspects, collecting evidence, and funding the court’s activities.

Disappointingly, participants in Kampala failed to use the Review Conference as a platform to improve the performance of the Court. African States argued the ICC had improperly focused its efforts on Africa, and questioned the premise that justice for atrocity crimes is compatible with peace in post-conflict societies, a tenet central to the ICC’s existence.

Developing states demanded that the ICC direct efforts at improving the capacity of national courts to prosecute atrocity crimes, an effort requiring development aid well beyond the capacity of the already stretched Court.

Instead of addressing performance deficiencies, these same states directed the Review Conference toward determining whether and how the Court would exercise jurisdiction over the crime of aggression. Jurisdiction over aggression would give the ICC the power to hear claims against leaders of states accused of using military force inconsistently with the U.N. Charter.

For states not represented on the U.N. Security Council, this authority was conceived as a counterbalance to the Council that they hoped would be more accountable to their concerns. Not surprisingly, the permanent members of the Security Council including the United States, opposed these efforts to undermine the Council. Supporters of the Court also worried about the impact on the Court of being drawn into politicized disputes about the lawfulness of the decision to use force. These divisions resulted in the participants deferring a decision on aggression until after 2017.

Given the political posturing of many parties to the Court in Kampala, the United States must decide whether continued engagement with the ICC makes sense.

Having led efforts to prosecute atrocity crimes since the Nuremberg trials after World War II, the United States has been a traditional supporter of an international court.

From a national security perspective an international criminal court can bolster U.S. efforts to stabilize post-conflict regions, as the International Tribunal for the former Yugoslavia did in the Balkans. And international prosecutions can give the United States political options in states where the use of force is not politically or practically feasible, as may be the case with Sudan. An international court is consistent with the U.S. commitment to enforcing human rights.

Nevertheless, fears of politicized prosecutions and dilution of Security Council power have caused successive administrations of both parties to keep the ICC at arms length.

This decision has hurt the ICC, as there is no substitute for the assistance the United States could provide the Court in apprehension of suspects, gathering evidence, and training prosecutors and judges.

But it also hurt the United States, as it allowed states with political agendas contrary to the interests of international justice to divert the Court from work that is also beneficial to the United States, as evidenced in the lead-up to Kampala.

Ironically, the very concerns that have kept the United States away from the Court now counsel for greater U.S. engagement. The United States was instrumental in achieving deferral on aggression in Kampala through forcefully advancing U.S. concerns about the impact of aggression on the Court and the United States.

It is unlikely this same result would have been reached without the United States present. Strong U.S. diplomacy in the years ahead is likely to be the only brake on an attempt to add aggression seven years from now.

U.S. membership in the ICC is unlikely in the foreseeable future, given the political realities of treaty ratification in the Senate. The gamesmanship of the other participants in Kampala suggests that this is good policy as well as good politics.

But there is no substitute for sustained U.S. engagement with the Court in ensuring that the ICC remains focused on prosecuting atrocity crimes, benefiting both it and the United States.

Vijay Padmanabhan is the author of a recent Council on Foreign Relations Special Report on the U.S. and the ICC. He is a Visiting Assistant Professor at Cardozo Law School, and was an Attorney-Adviser at the U.S. Department of State from 2003-2008.

Fox Forum is on Twitter.  Follow us @fxnopinion.