Gaps in fencing along the US-Mexico border can be a dramatic – and sometimes puzzling – sight.

Miles of tall steel bollards end abruptly, giving way to open space or much smaller barriers that are designed to block vehicles from crossing, but not people. Container House Expandable

Arizona Gov. Doug Ducey says he got tired of waiting for federal authorities to fill in the holes.

Crews at his direction started stacking shipping containers along portions of the border in August. Now the Bureau of Reclamation is asking the state to remove them – a request that Ducey’s office calls “unacceptable.”

Meanwhile, Arizona is starting to place shipping containers along another section of the border.

Here’s what we know about what’s happening, and a look at the bigger picture.

Ducey, a Republican, issued an executive order in August telling the state’s Department of Emergency and Military Affairs to use shipping containers to fill in gaps along the border. The first project: closing a 1,000-foot gap near Yuma, Arizona.

“Arizona has had enough,” he said at the time. “We can’t wait any longer.”

The 8,800-pound, 9-by-40-feet containers stand about 22 feet tall when stacked, welded together and topped with four feet of razor wire, the governor’s office said, while border fencing built during the Trump administration is about 30 feet high.

Shortly after the project began, two shipping containers toppled. A Univision reporter who shared photos of the fallen containers said contractors in the area had told her strong winds were to blame. Ducey’s office said they suspected foul play. Since then, no similar incidents have been reported, spokesman CJ Karamargin said.

By late August, 11 days after the first shipping container project began, officials announced that 130 stacked shipping containers were filling four gaps and covering more than two-thirds of a mile along the border in Arizona’s Yuma County.

That effort, Karamargin said, cost $13 million.

Constructing a bigger border wall was one of former President Trump’s signature priorities, and among the initiatives most criticized by his opponents. President Biden swiftly halted border wall construction once he took office.

But the Department of Homeland Security has said it plans to close small gaps in the wall. And in July, the Biden administration announced a plan to fill some gaps in the border wall near Yuma.

The Bureau of Reclamation cited those plans in a letter sent to Arizona officials earlier this month. The letter, obtained by CNN affiliate KYMA, asks the state to remove most of the shipping containers to make way for US Customs and Border Protection’s plans to fill in the gaps.

The letter says 80 containers were placed on Bureau of Reclamation land near the Morelos Dam and 42 were placed on Bureau of Reclamation rights of way on the Cocopah Indian Tribe’s West Reservation.

“The unauthorized placement of those containers constitutes a violation of federal law and is a trespass against the United States,” said the letter from Jacklynn L. Gould, a Bureau of Reclamation regional director.

Gould asked Arizona officials to remove the containers and “work with Reclamation, in consultation with the Cocopah Indian Tribe, so that CBP’s project may proceed without unnecessary delay.”

The Bureau of Reclamation did not respond to CNN’s requests for comment on the letter.

So far Arizona isn’t backing down from the effort.

The state’s director of emergency management sent a stern response to the Bureau of Reclamation, disputing allegations that Arizona had trespassed on federal land and stating that the shipping containers would remain in place “until specific details regarding construction are provided.”

“Since December 2021, numerous federal representatives have claimed that construction on the border would begin,” Allen Clark wrote. “However, to date, Arizona has not seen any action by the federal government to do so and was therefore required to take its own action.”

Karamargin told CNN that state officials recently received a letter from CBP describing plans to use mesh fencing to fill the gaps, something he described as “completely unacceptable.”

Triangle Roof Prefab House “From Gov. Ducey’s perspective, the idea that we would take down a temporary measure so that they can replace it with a less effective temporary measure in a nonstarter,” Karamargin said.