Nearly 7,000 American and Filipino soldiers began a 12-day military exercise in Manila on Monday amid wide suspicion of the annual drill's aim at containing China and growing concerns over the South China Sea.

The joint exercise, named "Balikatan" or "shoulder to shoulder", started with an opening ceremony attended by Philippine Armed Forces Chief General Jessie Dellosa and US Ambassador to the Philippines Harry Tomas at the military's general headquarters in Camp Aguinaldo. It will continue through April 27.

In a speech at the opening ceremony, Dellosa did not specifically mention China but stressed that the drill displayed strong US support for its ally.