The state of the union address is an annual event, where the president updates congress on past achievements and lays out the plans for the year ahead.
Obama's main pitch for 2013 is the economy but the Afghanistan drawdown is among his top priorities from even before he began his presidency in 2009.
The US will be out of Afghanistan by 2014 end, leaving behind a residual force for training Afghan forces and counter-terrorism operations. The size of that force has not been announced yet.
The US and Afghanistan speeded up the withdrawal announcing in January. Afghan forces will start taking lead responsibility for security from coming spring, ahead of schedule.