Festivities in Iraq were marred by a car bomb in Kirkuk on "National Sovereignty Day" proclaimed by President Nouri al-Maliki.

In Baghdad there were festive fireworks, decorations on blast walls and a party in a park, but many Iraqis stayed home, perhaps choosing the safest way to mark the withdrawal of U.S. combat troops from Iraq's cities.

Full control of security now belongs to 600,000 Iraq army and police personnel. No longer will the 130,000 American troops still in Iraq go on routine patrol, although they are on call with helicopter gunships, surveillance aircraft and other types of assistance.

Thanks in part to the troop surge that started two years ago, Iraqis have a chance to continue rebuilding their country on their own.

But it's only a chance. Although fewer Iraqi civilians were killed in May than in any month since 2003, there was an upsurge in violence in June. The country is still riven by sectarian differences.

Baghdad, for example, is still more dangerous than Kabul, as The Independent noted in Great Britain. Few of the estimated 2.2 million Iraqi refugees have returned.

For Iraqis to succeed, the United States needs to continue working with Iraqis to find ways for the political factions to bridge their differences and continue rebuilding their economy. U.S. diplomats must become more involved in bringing Iraqi leaders together.

One flashpoint is between the Kurds in the semi autonomous provinces in the north and al-Maliki's central government.

Kurds believe they are entitled to control over the city of Kirkuk and its province. The Iraqi Constitution approved four years ago called for a vote to settle Kirkuk's status, but the vote has never taken place. The United Nations earlier this year suggested that the province have its own regional government run jointly by Kurds, Arabs and Turkmens.

Another flashpoint is between the Shiites and Sunni muslims. Sunnis, who held power under former dictator Saddam Hussein, are resentful at being shut off from power. The Sunni Awakening Councils that helped fight al-Qaida during the surge deserve much credit for helping reduce violence.

There are discouraging signs, however, that Shiites continue to resist moves to allow the Sunnis to share in governance. Some Awakening Councils, for example, say they have still not been paid as promised for their efforts.

Symbolic of the split between the factions is the Iraqi Parliament's inability to pass a law on how to divide oil revenue.

Despite these schisms, the first National Day of Sovereignty was still a day of hope. If the Iraqis can find the will to reconcile their differences, the holiday might in the future be marked by genuine celebration.