President Trump said his administration is ready to help Mexico “wage WAR” against drug cartels in the country after nine US citizens, including three women and six children, were slaughtered after being caught in the crossfire of warring gunmen on Monday.

“A wonderful family and friends from Utah got caught between two vicious drug cartels, who were shooting at each other, with the result being many great American people killed, including young children, and some missing,” the president wrote on Twitter Tuesday.

“If Mexico needs or requests help in cleaning out these monsters, the United States stands ready, willing & able to get involved and do the job quickly and effectively,” he continued.

Trump said new Mexican President Andres Manuel Lopez Obrador has made the cartels “a big issue” but noted that they have become “so large and powerful that you sometimes need an army to defeat an army!”

“This is the time for Mexico, with the help of the United States, to wage WAR on the drug cartels and wipe them off the face of the earth,” the president said in another posting. “We merely await a call from your great new president!”

At a news conference, Lopez Obrador said he would speak with Trump about the violence but rejected his offer to strike at the cartels.

It’s not in agreement with our convictions. The worst thing you can have is war,” he told reporters.

“We declared war, and it didn’t work,” Lopez Obrador said, referring to the military responses taken by previous administrations. “That is not an option.”

The White House later Tuesday confirmed the two leaders talked about the attack and “efforts to combat the growing violent behavior of cartels and criminal groups in the region.”

The victims, dual US-Mexican citizens with ties to Utah, were caught in the crossfire in the northern border state of Sonora near where they worship with Church of Jesus Christ of Latter-day Saints.

The victims were identified by a relative as Christina Marie Langford Johnson, 29, Dawna Langford, 43, Trevor Langford, 11, Rogan Langford, 2, Rhonita Maria Miller, 30, Howard Miller, 12, Krystal Miller, 10, and 8-month-old twins Titus and Tiana Miller.