If the 19th and early 20th century marked the era of unification with the creation of a united Germany and a united Italy, a united Yugoslavia and a united Czechoslovakia, then the late 20th and early 21st centuries may go down in history as the era of disintegration.
Yugoslavia, which Marshal Tito had virtually willed into being, broke up into Serbia and Montenegro, Croatia, Slovenia, Macedonia, and Bosnia and Herzegovina. Czechoslovakia divided into the Czech Republic and Slovakia. The Soviet Union fragmented into Russia and 14 other republics.
And now there's Iraq, where United Nations envoy Ashraf Qasi says that sectarian violence is the No. 1 problem, "more than the insurgency." And Gen. John Abizaid, head of the central command, also sees sectarian violence as a greater threat than the insurgency.
The nonprofit, nonpartisan International Crisis Group says in its Middle East Report that the international community, including Iraq's neighboring states, should start preparing for the contingency that Iraq will fall apart.
"Neighboring states," says the report, "may forsake their longstanding commitment to Iraq's territorial integrity if they conclude that its disintegration is inevitable, intervening directly in whatever rump states emerge from the smoking wreckage."
Iraq was, in a sense, an artificial construct to begin with, the majority Shiites and the Kurds persecuted by minority Sunnis under Saddam Hussein.
The effort to erect a democratic state uniting the three main sectarian elements has been real, and it goes on, but it is threatened by a developing cycle of sectarian violence and counter-violence.
What is clear is that it will be harder to contain the sectarian struggle than to contain the insurgency. And over all hangs the danger of civil war and the disintegration of Iraq.
• Daniel Schorr is a senior news analyst at National Public Radio.