(Donald Trump, then a Republican presidential candidate, at a news conference near the US-Mexico border outside Laredo, Texas.Reuters/Rick Wilking)
President Donald Trump looks set to ask Congress for more than $4 billion for his much-touted border wall, and proposal requests issued by the Department of Homeland Security have asked for a "physically imposing" wall at least 30 feet high.
But recent comments from Trump's interior secretary, Ryan Zinke, cast doubt on just how imposing parts of that wall would be — if they get built at all.
"The border is complicated, as far as building a physical wall," Zinke told the Public Lands Council, which represents Western ranchers, on Tuesday in comments first reported by E&E News.
"The Rio Grande, what side of the river are you going to put the wall?" he said. "We're not going to put it on our side and cede the river to Mexico. And we're probably not going to put it in the middle of the river."
Some areas may be more amenable to electronic defenses, Zinke told attendees. Other spots with imposing physical features may end up not needing additional barriers. The border is already dotted with sensors and monitors, as well as about 700 miles of fencing.
Since Trump first began touting his wall idea on the campaign trail, numerous observers have pointed out how the terrain along parts of the 2,000-mile border either negated the need for a wall or would make building it difficult if not impossible.
(Trump speaking at the Environmental Protection Agency, with Vice President Mike Pence, EPA chief Scott Pruitt, and Interior Secretary Ryan Zinke.AP Photo/Pablo Martinez Monsivais)
Parts of the frontier in Arizona are wild and treacherous, making crossing dangerous. (The US border patrol has been accused of using these areas as a "weapon" against crossers.)
Parts of Texas' border with Mexico, which covers about 1,200 miles, are marked by high cliffs and deep canyons. The Rio Grande, a river that delineates most of the Texas-Mexico frontier and marks the actual border in some places, widens into the 154-mile Falcon International Reservoir in eastern Texas.
Texas legislators have criticized the idea of a solid, physical barrier on the border or even the idea of a wall itself. (Trump surrogates suggested the wall could be technological during the campaign, but Trump's camp backed away from that idea at the time.)
(A newly built section of the US-Mexico border fence at Sunland Park, opposite the Mexican border city of Ciudad Juarez, seen January 26.REUTERS/Jose Luis Gonzalez)
"I don't know how that would work," Sen. John Cornyn, the No. 2 Republican in the Senate, told The Dallas Morning News. Cornyn opposes a full-length border wall. "When I hear the president talk about a wall, to me I think he's speaking metaphorically," he said.