US rivals Obama and Romney spar on foreign policy

US President Barack Obama and his Republican challenger Mitt Romney have battled over national security in the third and final presidential debate.

The rivals tangled over the Arab Spring, Iran's nuclear capabilities, China's growth and more in a feisty 90-minute head-to-head.

Mr Obama said his challenger was "all over the map" on foreign policy, while Mr Romney said the president had failed to uphold American global leadership.

Steve Kingstone reports from Washington.