Earlier this year, media reported that CBP created a list of 59 mostly American reporters, activists and attorneys to investigate into.
"A number of journalists and photographers were identified by Mexican Federal Police as possibly assisting migrants in crossing the border illegally and/or as having some level of participation in the violent incursion events… CBP followed through with appropriate investigatory queries," Howe told Center for Democracy and Technology attorney Mana Azarmi in a letter made public by the Intercept on Friday.
The effort to gather such information, he added, followed standard law enforcement practice. Howe also stressed that CBP did not unlawfully target journalists for their political views.
"CBP does not target journalists for inspection based on their occupation or their reporting… CBP has policies in place that prohibit discrimination against arriving travelers and has specific provisions regarding encounters with journalists," Howe said.
READ MORE: Paint It Black: Trump Wants Dark, Brutal Border Wall With Spikes − Reports
Crisis on the US southern border escalated last fall when a caravan which included thousands of people from Central American countries reached the US. Recent data from Customs and Border Protection showed that the CBP apprehended or turned away more than 109,000 migrants attempting to cross the border in April, marking the second month in a row the number has topped 100,000.
In late January, after month-long partial shutdown of government agencies due to Differences with Democratic lawmakers, Donald Trump declared a national emergency at the southern border in a move that enabled him to divert military funds toward border security.