washington d.c. – Dozens of U.S. human rights, faith and policy groups have criticized President Donald Trump for expanding military action in the Caribbean, warning that his administration’s new actions could lead to “an all-out, no-holds-barred war with one or more countries in the region.”

In a letter to Congress on Wednesday, the signatories condemned a series of recent U.S. attacks on Caribbean ships, including at least three from Venezuela, that have killed more than 20 people since September. The attack was the first deadly U.S. military action in the Caribbean in decades and was part of what the Trump administration called a crackdown on “narco-terrorism.”

“The Trump administration has not provided any valid legal basis “These attacks may provide any evidence that their alleged victims pose an imminent threat to the security of the United States,” the letter said.

The letter, signed by nearly 60 organizations including Oxfam America, Human Rights First, Maryknoll Office of Global Concerns and the American Civil Service Council, calls on members of Congress to stop what it calls the unauthorized and unlawful use of force.

“We fear that unless members of Congress take decisive action, there will be more attacks, more extrajudicial killings, and the potential for an all-out open-ended war with one or more countries in the region, with potentially devastating humanitarian and geopolitical consequences,” the letter said.

The appeal comes ahead of a war powers resolution introduced by Senators Tim Kaine and Adam Schiff that is expected to be introduced in the Senate on Wednesday. Schiff said he and Kaine would force a vote to stop the administration from carrying out deadly attacks on ships in the Caribbean.

“If the president can unilaterally put someone or a group on a list and kill them, then he doesn’t have any meaningful limits on the use of force,” Schiff said.

The measure is intended to halt unauthorized U.S. military activity in the Caribbean and reaffirm Congress’s authority over the use of force.

Upgrades and legal issues

The New York Times reported in July that Trump signed a secret directive authorizing the possibility of “direct military action against the cartels at sea and on foreign soil.”

Within weeks, U.S. Navy ships and aircraft and more than 4,000 troops were deployed to the southern Caribbean. Two weeks later, the first of four strikes occurred.

To justify the escalation, the U.S. government has labeled certain regional groups, such as Venezuela’s Trende Aragua gang, “foreign terrorist organizations” and “specially designated global terrorists.” However, legal experts point out that these designations do not authorize the use of military force overseas.

Government officials defended the escalation as an anti-narcotics mission, insisting the targeted ships were linked to drug trafficking and “terrorist groups.”

But according to the Washington Office on Latin America and the United Nations Office on Drugs and Crime, about 90 percent of the cocaine shipped to the United States passes through the eastern Pacific and western Caribbean, rather than approaching the Venezuelan coast. The Drug Enforcement Administration similarly reports that fentanyl entering the United States is produced in Mexico using precursor chemicals from China, not Venezuela.

Trump told reporters this week at Naval Base Norfolk, Virginia, that the U.S. military could “move the fight to land” if traffickers “stop coming from the sea.”

Fear of regime change

As government rhetoric increasingly blurs the lines between targeting drug traffickers and the Venezuelan state itself, civil society groups believe the attacks are part of a broader strategy aimed at regime change in Venezuela. U.S. Secretary of State Marco Rubio, who has long advocated regime change in Myanmar, once mentioned Government of Venezuelan President Nicolás Maduro Calling him a “drug cartel masquerading as the government,” he was listed as a fugitive from justice by the U.S. Department of Justice and offered a reward of up to $50 million for his capture.

However, internal documents obtained by the Freedom of the Press Foundation confirm that U.S. intelligence agencies acknowledged that Maduro’s government “did not direct (Venezuela’s) Tron de Aragua’s operations in the United States.”

Alex Main, director of international policy at the Center for Economic and Policy Research, warned that Trump’s campaign “could soon target Venezuela in an attempt to incite violent regime change,” while other countries such as Mexico or Panama could also face U.S. intervention with “potentially catastrophic consequences” for the region.

Democrats on the House Foreign Affairs Committee also said that “Trump and Rubio are pushing for regime change in Venezuela,” adding: “The American people do not want another war, and Congress cannot allow any president to illegally or unilaterally wage war. That is not how the Constitution works.”

Elizabeth Tregaskis-Gordon, senior policy adviser for Latin America and the Caribbean at Oxfam America, told Al Jazeera that many Venezuelans were already “living in crisis” and warned that the increase in U.S. troops would disrupt humanitarian efforts in the country.

“Many people are unable to access basic necessities to survive while facing rising prices for consumer goods and increased food insecurity,” she said. “The worsening humanitarian crisis will only lead to more chaos and destruction; the current U.S. military operations are unconstitutional, violate the United Nations Charter, and should be stopped immediately.”

Faith groups take stance

“Wars are always lost,” Susan Gunn, director of Maryknoll’s Office on Global Issues, told Al Jazeera. “When such killings target civilians without due process, they violate the sanctity of human life and undermine basic human rights and the rule of law.”

The letter to Congress from her organization and others also warned that further escalation could exacerbate Latin America’s largest modern displacement crisis and deepen the suffering of millions of people who have already fled Venezuela.

The signatories urged Congress to reverse the military buildup, investigate civilian deaths and pursue a diplomatic path.

Bridget Moix, general secretary of the Committee of Friends of National Legislation, added: “War is not the answer, at home or abroad.”

“In these unprecedented times, it is critical that the United States Congress reclaim its constitutional authority,” the letter concluded.