More than 80 people have been killed in the Trump administration's months-long campaign against alleged drug traffickers.
US authorities have not provided specific evidence that the targeted boats were ferrying drugs.
Governments that partner with the United States on counternarcotics efforts should assess whether intelligence sharing "risks making them complicit in the strikes," the advocacy group said in a statement, labeling the attacks "unlawful extrajudicial killings."
"The rules-based international order depends on countries speaking out against violations, even when they're committed by powerful friends," said Sarah Yager, Human Rights Watch's Washington director.
The group listed Canada, Britain, France and the Netherlands among countries it said should be more vocal in condemning the campaign, which has divided lawmakers on Capitol Hill and put pressure on top officials.
US Defense Secretary Pete Hegseth has distanced himself from an operation in which a second strike hit survivors of an initial attack on an alleged drug smuggling boat in the Caribbean.
The White House said a US admiral acting under Hegseth ordered the follow-up attack.
Human Rights Watch said that France, Britain and the Netherlands "have significant influence in the Caribbean" and should "perform due diligence and evaluate their maritime cooperation" with Washington's military campaign.
"Under both US and international law, those accused of crimes should be arrested and tried, not summarily executed," the rights organization said.
Related Links
21st Century Pirates
| Subscribe Free To Our Daily Newsletters |
| Subscribe Free To Our Daily Newsletters |
