Mexico and the United States have deployed thousands of troops to their 3,100-kilometer (1,900-mile) frontier since President Donald Trump returned to office in January, when he immediately declared a border "emergency."

The efforts appear to be paying off: the US Customs and Border Protection (CBP) reported a 65-percent drop in migrant interceptions in January compared with the same month of 2024.

"If before there were a hundred daily crossings, now there are no more than five. Yesterday there were none," a Mexican National Guard officer told AFP during a patrol on the edge of the border city of Tijuana.

The officer, who spoke on condition of anonymity, attributed the fall to coordination between US and Mexican border patrols, including a WhatsApp chat in which they share data, photos and videos of their operations.

Mexico has stepped up efforts to contain fentanyl trafficking and illegal migration to the United States, seeking to address two issues that Trump used to justify the 25-percent tariffs that he imposed on Mexican goods.

After a call Thursday with Mexican counterpart Claudia Sheinbaum, Trump agreed to suspend most of the duties until April 2.

The two countries were "working hard, together, on the Border, both in terms of stopping Illegal Aliens from entering the United States and, likewise, stopping Fentanyl," he wrote on his Truth Social platform.

- Military camp -

Armed Mexican troops patrolled the steep slopes of an area on the edge of Tijuana known as Eagle's Nest, a well-known crossing point for migrants who are often guided by traffickers.

On the other side of the border, to the west, was the US city of San Diego, about 15 hours away on foot.

Since February 20, about 30 soldiers have set up camp next to the border, on a hill surrounded by ramshackle homes, dirt roads, chicken coops and garbage.

Due to the rocky terrain, there is no wall along this part of the border, making it a key crossing point, the National Guard officer said.

Despite the increased military presence, some migrants still risk trying to cross, like a Pakistani couple intercepted on February 26 with a child in their arms.

They were handed over to the Mexican immigration authority, after the National Guard had the CBP check whether the adults had criminal records.

"From the wall here, they are ours; from the wall there, they are theirs," the officer said about the demarcation of the border for intercepting migrants.

Meanwhile, his troops filmed CBP helicopter overflights to share in the group chat.

One of them has stuck a CBP patch on his helmet, a common gesture among law enforcement officers who exchange emblems as a symbol of friendship.

On the US side of the fence, meanwhile, soldiers pushed a large roll of barbed wire uphill to use to reinforce the barrier, while others surveyed Mexican territory with binoculars.