The toddler is believed to be the first successful intruder across the White House fence, which was installed in 2022.

The toddler slipped through the fence on Tuesday morning, prompting officers from the United States Secret Service Uniformed Division to walk across the executive mansion’s North Lawn to intercept the youngster.

Access to the public area of the complex was briefly restricted as the officers worked to return the toddler to his parents on Pennsylvania Avenue.

Secret Service spokesman Anthony Guglielmi said officers “encountered a curious young visitor along the White House north fence line who briefly entered White House grounds”.

“The White House security systems instantly triggered Secret Service officers, and the toddler and parents were quickly reunited,” he said in a statement.

The National Park Service constructed a new fence in front of the White House in 2022, replacing the two-metre-tall (6.6-foot) fence with a nearly four-metre (13-foot) one.

The National Park Service said “the new fence incorporates anti-climb and intrusion detection technology and is designed to mitigate current and future security threats”.

While taller, the new fence has an additional inch of space between pickets, for a total of 14cm (5.5 inches) between posts — just enough clearance for a pint-sized interloper to slip through.

The toddler’s foray into the executive branch may be the first successful intrusion onto the complex since the new fence was installed, the Associated Press noted.

Older children have at times become stuck in the barrier, which has also been the scene of demonstrations, with protesters chaining themselves to the fence.

Prior to the fence’s replacement, attempts — some successful — to vault the barrier had been relatively common.

A man draped in an American flag did so on November 25 during a Thanksgiving celebration at the mansion.

In 2017, authorities found 38-year-old Marci Wahl hanging from her shoelaces inside the fence on the south side of the White House. She had apparently become stuck as she sought to scale the posts.

The Secret Service did not immediately have comment on the incident with the toddler. Officers briefly questioned the parents before allowing them to continue on their way.