The US President is discussing the possibility of sending artillery units to the hotly contested region – where China is said to be building military bases on artificial islands.
A senior US defence chief has said the plan to install defensive gun positions in the region could soon go ahead.
The source said: “A Howitzer can go where it has to go. It is a way of changing an offensive weapon and using it in dual capacity.
“This opens the door to opportunities and options we have not had before with mobile defensive platforms and offensive capabilities.”
Officials suggest similar weapons could be used in Eastern Europe to challenge Vladimir Putin.
The potential deployment raises the worrying prospect of clashes between U.S. forces and Chinese jets, which are readily dispatched to islands controlled by Beijing.
The Chinese government has already accused Washington of stirring tensions in the volatile region – and an increased U.S. presence could set the two superpowers on a collision course.
American troops have conducted several joint exercises with regional allies such as Japan in a show of force against China.
The Pentagon has also authorised a series of “freedom of navigation” exercises close to China”s military bases.
President Obama said this weekend that he would continue to challenge the communist state”s territorial claims.