Despite ongoing international crises in war zones like Syria, Iraq, and Afghanistan, Mexico quietly climbed to the top of the world’s deadliest countries for 2016. In its annual report on armed conflict, the International Institute for Strategic Studies (IISS) showed that 23,000 people were killed in Mexico in 2016, the highest number of any country in the world second only to Syria, where an ongoing civil war has killed thousands and has included the use of weapons of mass destruction on the battlefield.

“This is all the more surprising, considering that the conflict deaths [in Mexico] are nearly all attributable to small arms,” said John Chipman, chief executive and director-general of the IISS.

“The conflict in Mexico led to 23,000 fatalities in 2016, with the number of homicides rising in 22 of the country’s 32 states,” the report reads. “The largest rises in fatalities were registered in key battleground states, where competing, increasingly fragmented cartels vie for control. The violence grew worse as the cartels expanded the territorial reach of their campaigns, seeking to ‘cleanse’ areas of rivals in their efforts to secure a monopoly on drug-trafficking routes and other criminal assets.”

Mexico has scored several high-profile victories against the world’s most violent and prolific drug cartels operating within their borders. Last year’s capture of Sinaloa Cartel leader Joaquin “El Chapo” Guzman was heralded as a major breakthrough in Mexico’s war on drugs, which has been led by its military for over a decade. Last week, his successor, Damaso Lopez Nunez, was arrested in Mexico City. Nunez has reportedly been locked in a violent power struggle with Guzman’s sons, who are vying for control of El Chapo’s criminal empire.

But despite major arrests and a militarization of the conflict, the violence has only grown worse and spread in the country. In 2014, 15,000 deaths were reported, rising to 17,000 in 2015, according to the IISS.

The issue of cartel violence has become a priority of President Donald Trump, who said he had discussed the possibility of sending U.S. military assets, including soldiers, to assist Mexico in dismantling the cartels. Trump spoke with Mexican President Pena Nieto via a phone call in February.

“You have a bunch of bad hombres down there,” Trump said during the call. “You aren’t doing enough to stop them. I think your military is scared. Our military isn’t, so I just might send them down to take care of it.”

Another theme to emerge in 2016 is the increasing urbanization across all armed conflict. As populations grow and densely pack urban areas, conflict similarly moves into the cities. Wars in Turkey, South Sudan, Afghanistan, Syria, and Pakistan—to name a few—all included instances of conflict increasingly focusing on cities.