One of President Trump’s wildest – and, unfortunately, most popular – campaign promises was to fight immigration and have Mexico pay to build a wall along America’s southern border. Just visualizing a giant wall stretching across the border is ridiculous.

Today, Trump plans to sign an executive order to follow up on that promise. 

Despite the president’s passion for the project, many questions still remain unanswered about how building the wall will work. For example, how long will it be? Because building a wall with gaps in it makes it completely useless. More importantly, whose going to pay for it? Originally, Trump declared that he’d find a way to make Mexico pay for its construction, which isn’t likely.

Trump’s personal crusade of building “the wall” is only the tip of the iceberg when it comes to his views on immigration and foreign relations, according to reports from The New York Times. In the coming days, he’s expected to also decide on the future of Guantanamo Bay, the use of CIA “black sites,” what to do with Syrian refugees and whether or not there should be a temporary freeze on the immigration of people from “terror prone” nations.

Gil Kerlikowske, who served as Commissioner of Customs and Border Protection under President Obama, told CNN that Trump’s efforts to build a wall have their noticeable flaws.

“The border and migration issues are just unbelievably complex,” Kerlikowske said. “And a simple answer to a complex problem is most assuredly the wrong answer.”

Not only does Kerlikowske feel that the terrain along the border – which includes the Arizona desert and Rio Grande – make building a wall difficult, he also confirmed that there’s already plenty of security in place along the border. Which leads one to believe that Trump’s wall would mostly be an ineffective eye sore meant to please his racist base.

Mexican President Enrique Peña Nieto will meet with Trump later this month as one of the first foreign leaders to do so.