US forces have killed 14 people in strikes on four alleged drug boats in the Pacific, Defence Secretary Pete Hegseth said.

Mexico's navy says it is still searching for a lone survivor approximately 400 miles (643km) from the Pacific coastal city of Acapulco.

It is the latest in a series of attacks on boats the US says have been carrying drugs in both the Pacific and Caribbean.

The latest strikes in the eastern Pacific, which Hegseth said happened on Monday at the direction of President Donald Trump, mark an escalation in what it has cast as a campaign to stop narcotics from entering the US.

The strikes have drawn condemnation in the region and experts have questioned their legality. Members of the US Congress, both Democrats and Republicans, have also raised concerns and questioned the president's authority to order them.

Mexican President Claudia Sheinbaum told her morning press conference "we do not agree with these attacks". She said she had asked the country's foreign minister, as well as representatives of the navy, to meet the US ambassador.

"We want all international treaties to be respected," she added.

At least 57 people have now been killed in the strikes, which has led to increasing tensions between the US and the governments of both Colombia and Venezuela.

Most strikes have taken place off the coast of South America, in the Caribbean, but recently the US has turned its attention to the Pacific Ocean as well.

In a statement on X, Hegseth said the four vessels that were hit on Monday "were known by our intelligence apparatus, transitioning along known narco-trafficking routes and carrying narcotics".

He added that eight "narco-terrorists" were killed in the first strike. Four and three were killed in the following two strikes.

One person survived the strikes. According to Hegseth, Mexican search-and-rescue authorities "accepted the case and assumed responsibility for coordinating the rescue."

The condition of the survivor or his current whereabouts are unclear. Mexico's navy said in a statement that it had dispatched a patrol boat and an aircraft to conduct search operations to "safeguard human life at sea".

Hegseth's post included videos that show several vessels catching fire after being struck by US munitions.

"The department has spent over two decades defending other homelands," he wrote. "Now, we're defending our own."

At least four of the strikes have so far taken place in the Pacific, which is a far more significant drug-trafficking corridor, with the rest taking place in the Caribbean.

President Trump has said he has the legal authority to continue bombing boats in international waters, but suggested last week that he may seek approval from Congress if the campaign is expanded to include targets on land.

Trump has said he is "totally prepared" to strike land-based targets, which would mark a significant escalation in the campaign.

The strikes, however, have drawn criticism from international law experts and both the Venezuelan and Colombian governments.

Mary Ellen O'Connell, an international law expert at Notre Dame University and former military educator with the defence department, said the "criminal suspects are entitled to due process".

"It is a greater crime to summarily execute people suspected of drug trafficking than drug trafficking is," she added.

In an interview with the BBC's Newsday programme last week, Colombian Deputy Foreign Minister Mauricio Jaramillo said the strikes were "disproportionate and outside international law".

Jaramillo said those on the vessels had "no possibility to defend themselves" and were struck with "no process" and "no judicial order".

The strikes also come as tensions ratchet up with both governments. The US has placed sanctions on Colombian president Gustavo Petro, accusing him of failing to curb drug trafficking and allowing cartels to "flourish".

In the Caribbean, the US has deployed troops, aircraft and naval vessels and last week ordered the world's largest warship - the USS Gerald R Ford - to the area.

Trump has accused Venezuelan President Nicolas Maduro of being the leader of a drug-trafficking organisation, which he denies, and there are fears in Venezuela that the US military build-up is aimed at removing the long-time opponent of Trump from power.

The country's attorney general told the BBC there is "no doubt" that Trump is trying to overthrow the Venezuelan government. He accused the US of hoping to seize the country's natural resources, including reserves of gold, oil and copper.

The US is among many nations that do not recognise Maduro as Venezuela's legitimate leader, after the last election in 2024 was widely dismissed as neither free nor fair. Opposition tallies from polling stations showed its candidate had won by a landslide.