One day in July, Rafiq slipped out of the world's largest refugee settlement in southern Bangladesh and crossed the border into Myanmar on a small boat. His destination: a ruinous civil war in a nation that he had fled in 2017.

STORY: Cox's Bazaar in Bangladesh is home to more than a million Rohingya refugees who fled persecution in Myanmar's western Rakhine state.But now it appears that thousands of Rohingya refugees have been recruited by militant groups and some are heading back across the border in Myanmar.

Rohingya refugees in Bangladesh join armed struggle in Myanmar, raising concerns of escalating violence and regional involvement.

The emergence of Rohingya fighters and weapons in camps is regarded as a ticking time bomb by Bangladesh, one source said