Political turmoil has escalated after Vice President Sara Duterte claimed to have arranged for President Ferdinand R. Marcos Jr.’s assassination if she is slain.

A major political storm set off by a bitter feud between the Philippine president and the vice president is testing an Asian democracy that has long been troubled by rowdy politics, poor law enforcement and bareface impunity.

Philippine President Ferdinand Marcos vowed on Monday to fight back against what he called reckless and troubling threats against him, speaking out after his estranged vice president said he would be assassinated if she herself were killed.