Representatives from the Border Patrol union are complaining that President Donald Trump's deployment of National Guard troops to the US-Mexico border has had "no benefit."

The deployment has so far been a "colossal waste of resources," Brandon Judd, president of the National Border Patrol Council, told The Los Angeles Times.

The troops have not been permitted to do tasks that they performed during previous deployments under the Obama and Bush administrations, Judd said.

The head of a union representing 15,000 Border Patrol agents said that President Donald Trump's deployment of National Guard troops to the US-Mexico border has been "a colossal waste of resources" that has yielded "no benefit."

Brandon Judd, president of the National Border Patrol Council, told The Los Angeles Times that the troops have been doing far less than they did during previous deployments, which occurred under former presidents Barack Obama and George W. Bush.

"When I found out the National Guard was going to be on the border I was extremely excited," Judd said, recalling how deployments in 2010 and 2014 helped ease the workload of Border Patrol agents. "That has not happened at all" this time, he added.

Though National Guard troops were never allowed to arrest or detain migrants, under previous deployments they were stationed in lookout and observation posts, and graded roads, and mended fences, Judd said.

Arizona National Guard soldiers line up as they get ready for a visit from Arizona Gov. Doug Ducey prior their deployment to the Mexico border at the Papago Park Military Reservation Monday, April 9, 2018, in Phoenix. Associated Press/Ross D. Franklin This time, they're "not allowed to be in the public eye," Judd said.

For instance, in the Rio Grande Valley, the busiest area for drug smugglers and migrants, the troops are stationed far from the border and duplicate rather than reduce Border Patrol agents' work, another union spokesman Chris Cabrera told The Times.

"We generally support the administration, but we're not going to be cheerleading when things are not going well," Judd said.

A spokeswoman for the Department of Homeland Security, Katie Waldman, told The Times that the deployment has not yet reached full capacity, but has "clearly and unquestionably been a success with thousands of additional apprehensions and millions of dollars of drugs kept out of our country."

By operating support technology and equipment, troops have so far contributed to nearly 4,000 deportations, 1,116 "turn backs" where migrants abandoned their attempts at crossing the border, and the seizure of nearly 3,500 pounds of marijuana, a Border Patrol spokeswoman said.

The deployment is expected to cost up to $252 million this year, according to the Pentagon. Trump has said he wants as many as 4,000 troops to be deployed ultimately.