The United States Department of Defence’s internal watchdog has launched a formal evaluation into lethal strikes conducted by US Southern Command against suspected drug-smuggling vessels.The announcement follows intense bipartisan criticism regarding the legality of the operations.The probe, announced on Monday by the Pentagon’s Office of the Inspector General (OIG), will scrutinise “Operation Southern Spear,” a controversial military campaign launched in late 2025 aimed at dismantling maritime drug trafficking routes in the Caribbean and Pacific.According to Pentagon data, the campaign has resulted in the destruction of 59 vessels and the deaths of 193 people since its inception last autumn.The Trump administration launched the operation with the declared aims of “detecting, disrupting, and degrading transnational criminal and illicit maritime networks.”Both Democratic and Republican lawmakers have questioned whether the military has the legal authority to use lethal force against civilian-style vessels in international waters outside of a declared theatre of war.Last month, the US Southern Command doubled down on the strikes despite the rising pushback.Its commander, General Francis L. Donovan, said: “Joint Task Force Southern Spear continues to conduct decisive operations to detect, disrupt, and dismantle narco-terrorist networks. In support of the President’s directives, the U.S. Coast Guard’s Maritime Security Response Team, accompanied by U.S. Marine Corps Special Purpose Forces, continue to support maritime interdiction operations to target the dark fleet that is enabling U.S. adversaries across the globe.”The OIG told Euronews in an email that the scope of the evaluation includes the joint process for targeted vessels in the US Southern Command area of responsibility as part of Operation Southern Spear and that the project was self-initiated based on the OIG’s ongoing assessment of Pentagon programmes and operations.The deadly strikes have marked a stark shift in the US approach to drug trafficking, which has historically focused on interdicting vessels and seizing the material.The US military, to date, has not provided any evidence that any of the vessels targeted were carrying drugs.