Mexican President Andrés Manuel López Obrador slammed U.S. lawmakers on Thursday for suggesting military action against Mexican drug cartels, after two Americans were killed in a kidnapping across the border last week.

“We are not going to allow any foreign government to intervene, much less a foreign government’s armed forces,” López Obrador told reporters during a press conference.

“We are not a protectorate of the United States, nor a colony of the United States,” he added. “Mexico is a free, independent, sovereign state.”

Four Americans were kidnapped by armed men just across the border in Mexico last week, after traveling to obtain a medical procedure. Two of the Americans died in the kidnapping, while one was injured and another remained unharmed. A Mexican citizen was also killed in the initial shootout.

A Mexican cartel, known as the Gulf cartel, has reportedly claimed responsibility for the kidnapping, according to The Associated Press. The group condemned the violence in a recent letter obtained by the AP and said it planned to turn over those involved to the authorities.

In the wake of the kidnapping, Sen. Lindsey Graham (R-S.C.) said that he was prepared to introduce legislation to designate certain Mexican cartels as foreign terrorist organizations and “set the stage to use military force if necessary.”

“I would tell the Mexican government if you don’t clean up your act, we’re going to clean it up for you,” he told Fox News on Monday.

Rep. Dan Crenshaw (R-Texas), who introduced a resolution in January to allow for the authorization of force against cartels in Mexico, doubled down on his effort following the kidnapping.

“Our goal is to help the Mexican people rid themselves of violent cartels and the corrupt politicians who take their money,” Crenshaw said in response to a critical tweet from the Mexican senate’s majority leader. “If you’re against that, I’m against you.”

However, such military action would require an Authorized Use of Military Force that would have to pass a divided Congress and be signed into law by President Biden, who has previously committed to working with Mexico to stop illegal drug trafficking.