Washington (AFP) - As the Republican race for the White House in 2024 ramps up, threats by the party's presidential candidates to launch military strikes on Mexico's drug cartels are being taken increasingly seriously, sparking worries on both sides of the border.

In the party's election debate last week, Florida Governor Ron DeSantis -- a distant second in the polls to former president Donald Trump -- said that, if elected, he would send US forces in to dismantle Mexican drug labs "on day one."

Shortly after the debate, DeSantis doubled down: "When I talk about using the military to take on the drug cartels, because they're killing tens of thousands of our citizens, we have every right to do it."

Trump, who skipped the debate, has made some of the strongest calls for military strikes.

Rolling Stone reported recently that he asked advisors for military "battle plans" to unleash against Mexico if he is reelected next year.

Three other candidates, Vivek Ramaswamy, Nikki Haley and Tim Scott, have also endorsed the idea.

In March, Haley -- a former US ambassador to the United Nations -- said that the US should address Mexican traffickers as it does the Islamic State jihadist group. 

"We can do that by putting special ops in there... just like we dealt with ISIS, you do the same thing with the cartels," she said.

Foreign policy experts are warning that the calls need to be taken seriously, and that they comprise a dangerous threat to Washington's always tenuous relationship with its crucial southern neighbor.

"It's sheer lunacy," former Mexican ambassador to the United States Arturo Sarukhan, now at the Brookings think tank in Washington, told AFP.

Fentanyl surge

It is not a new idea. During his 2017-2021 presidency, Trump expressed interest in undertaking cross-border strikes against the cartels.

But aides reportedly talked him out of it, and it was never considered a real policy option. 

What has changed since then has been the surge in deadly fentanyl flowing across the border from Mexico, feeding an epidemic of American drug overdose deaths. 

In addition, Sarukhan says that Mexican President Andres Manuel Lopez Obrador has curtailed cooperation with US authorities on the drug trade, illegal immigration and other issues.

As a result, Republicans are calling for the kind of surgical drone strikes and nighttime raids that US forces have undertaken against Islamic jihadist groups in countries such as Iraq, Syria and Somalia, with few diplomatic consequences.

Last year a Trump-aligned thinktank, The Center for Renewing America, issued a policy white paper saying that if Mexico City does not curtail the fentanyl trade, the president should mobilize the US military directly.

"The goal is to crush cartel networks with full military force," it said.

In January, Republicans in Congress proposed formal war powers for the president to order US troops to act unilaterally against Mexican drug gangs.

And in March, Republicans introduced legislation to designate nine cartel groups as "foreign terrorist organizations," a distinction that would enhance a president's ability to launch the US military against them.

Bluster

Brian Finucane, of the International Crisis Group, said the talk should not be dismissed as election bluster.

"The posturing carries real risks," Finucane wrote in July, including of a radical breakdown in cooperation between Mexico City and Washington that could further threaten US security.

"Such stunts in Congress and bellicosity on the campaign trail increase the likelihood that a future president may regard such an attack as a real option."

When talk of military action surged among Republicans earlier this year, Lopez Obrador called it "irresponsible" and "a lack of respect for our independence and sovereignty."

"We're not going to allow any foreign government to intervene, much less the armed forces of a foreign government," he said.

Sarukhan said the calls for US military action arise from a "perfect storm" -- the combination of a jingoistic surge in the buildup to next year's US election, and Lopez Obrador weakening cross-border collaboration.

The debate rhetoric was obviously "red meat" for voters, Sarukhan said.

However, he added, "I think that deep down, (the candidates) do believe in what they're saying."

A unilateral attack on Mexico would not be seen in the same way as a surgical counter-terror strike on the Islamic State group overseas, he said.

Instead, it would see Mexico do even less to stop the flow of migrants and drugs to the United States.

Mexico City would also likely cut intelligence sharing in battling militants, and basic bilateral issues like water-sharing pacts would be jeopardized, he said.

"It's an act of war, and it's a violation of international law," he said.