A lone camel walks in Niger's Tenere region in the south-central Sahara. (Jerome Delay/AP)

President Trump had a suggestion for how Spain could deal with Europe’s migration crisis during a recent meeting with Foreign Minister Josep Borrell, according to reports in the Spanish media.

The idea was simple: “Build a wall across the Sahara.”

El País and Europa Press reported this week that Borrell recalled Trump’s suggestion during a luncheon in Madrid on Tuesday. The Spanish Embassy in Washington did not immediately respond to a request for comment, but the Spanish Foreign Ministry told Britain’s Guardian newspaper that the accounts of Borrell’s comments were accurate.

According to those accounts, Borrell told his audience that Trump had compared the situation in northern Africa and the Mediterranean to that along the U.S. border with Mexico. During his campaign, Trump had promised to build a wall along the southern border with Mexico and force the Mexican government to pay for it.

Borrell said that he did not support a wall along the border between the United States and Mexico and that Spanish diplomats had told Trump that the situation was considerably different in scale anyway. Trump disagreed, according to Borrell’s recollection, adding that “the Sahara border can’t be bigger than our border with Mexico."

The White House did not immediately respond to a request for comment.

Though estimates vary, U.S. Customs and Border Protection says that the border between the United States and Mexico is roughly 1,900 miles long. Most estimates for the Sahara put it at about 3,000 miles long from east to west.

A wall across the Sahara would probably also involve building through several sovereign nations. The desert spreads over parts of 11 countries: Algeria, Chad, Egypt, Eritrea, Libya, Mali, Mauritania, Morocco, Niger, Sudan and Tunisia.

It was unclear from the Spanish media whether Trump was speaking in jest when he made the purported comments. Borrell had accompanied Spain’s King Felipe VI and Queen Letizia to the White House in June.

Spain has seen rising numbers of migrants and refugees arrive on its shores in recent months, the result of a crackdown on a central Mediterranean route between Libya and Italy. According to the International Organization for Migration, more than 33,000 people have arrived in Spain via the western Mediterranean in 2018 — three times as many as in the same period last year.

The left-wing government of Prime Minister Pedro Sánchez, in power since June, has attempted to welcome the new arrivals — accepting migrant rescue boats such as the MV Aquarius after Italy rejected them.

Borrell, who was president of the European Parliament from 2004 to 2007, has been critical of anti-immigration sentiment in Europe. “Everybody in Europe is being affected by this virus, fears of immigration,” he told The Washington Post during the June visit to the United States. “This is not the case of Spain.”

His comments at the luncheon this week appear to affirm, however, that migration and identity are the most important issues facing the continent.

“European societies are not structured to absorb more than a certain percentage of migrants, especially if they are Muslims,” he said, according to El País.

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