In 1858, Abraham Lincoln gave his country a harsh warning: "A house divided against itself cannot stand."

The United States were divided over slavery. And three years later, the country was divided literally. Eleven states in the South left and set up a new nation. 

In the civil war that followed, 620,000 people died. 

That war has left a deep wound. For some Americans, one event brought those dark days closer than ever before: a year ago today, 2,000 people stormed the US Capitol Building. 

Today, Joe Biden will address his country for the anniversary of that attack. He has said that he will "speak to the truth" of the event. 

Biden knows that many of the divides over which the country fought the civil war are still there. And some fear they might boil over once again. In a book out next year, political scientist Barbara Walter warns that the USA is "closer to a civil war than any of us would like to believe".

Walter believes that the USA is no longer a democracy. She points out that Republicans are passing laws that make it harder for their opponents to vote.

She thinks these moves will deepen the divides in American society, and could ultimately lead to war.

Others think a civil war is unlikely. Uprisings against the government usually only succeed where the military is weak. The US military is powerful and loyal. It could quickly put down any rebellion.

But other kinds of conflict could still break out. Some have warned of the risk posed by far-right groups like the Proud Boys. In 2020, one extremist group even plotted to kidnap a Michigan politician.

Yes: Many Americans already believe the electoral system is rigged against them and their country is being taken over. If only a small number of these people take up arms they could start a devastating war.

No: Most people, including Republicans, condemned the Capitol riots. There would be little support for a new insurrection, and the army would stamp it out easily.

Or...? A war is unlikely, but the USA is already seeing violent clashes between extremist groups. Many people could suffer and die in this low-intensity conflict, even if it does not become a war.