• A former national security adviser to Mike Pence blasted Donald Trump and Stephen Miller Friday.
• She claimed the pair actively worked against the visa process for Afghans who helped US troops.
• The US is now working to evacuate tens of thousands of Afghan allies

A former national security official blamed the Trump administration and former Trump adviser Stephen Miller's "racist hysteria" for impeding the visa application process for Afghans who worked with the US.

Olivia Troye worked as the homeland security and counterterrorism adviser to Vice President Mike Pence. In a Twitter thread Friday, she blasted the Trump administration for its handling of the Special Immigrant Visa (SIV) programs that provide a path to US residency for locals who worked with the US government in Afghanistan.

"There were cabinet mtgs about this during the Trump Admin where Stephen Miller would peddle his racist hysteria about Iraq & Afghanistan. He & his enablers across gov't would undermine anyone who worked on solving the SIV issue by devastating the system at DHS & State," Troye wrote.

Since the Taliban swiftly seized control of Afghanistan Sunday, the US has been struggling to evacuate Americans as well as tens of thousands of Afghan allies who have worked with the US over the past two decades.

The Biden administration has come under sharp criticism from both sides of the aisle for its handling of the US troop withdrawal and subsequent evacuations. But criticism has also been aimed at the Trump administration, including Miller in particular.

Troye said she worked on the SIV issue but got "nowhere" because allies of President Donald Trump and Miller at the Justice Department, Department of Homeland Security, and other security agencies "made an already cumbersome SIV process even more challenging."

She said many people within the administration believed the matter was urgent but that many were afraid to oppose the president's allies, adding that there were "many closed door meetings" strategizing how to address the issue.

"Trump had FOUR years-while putting this plan in place-to evacuate these Afghan allies who were the lifelines for many of us who spent time in Afghanistan," she said. "The process slowed to a trickle for reviews/other "priorities"-then came to a halt."

Read more: EXCLUSIVE: Documents reveal how Trump is spending taxpayer money on his postpresidential offices — from printer toner to Stephen Miller's salary

An Afghanistan War veteran told CNN this week that Miller "should be held accountable for war crimes" for opposing the resettlement of endangered Afghans, and that he was "complicit" in their deaths.

Miller is an advocate for strict immigration limits. In an appearance on Fox News Tuesday night, Miller said "those advocating for mass Afghan resettlement are doing so for political and not humanitarian reasons," adding that it would also be too expensive.

"The United States of America never, ever, made a promise, written or unwritten, to the people of Afghanistan that if after 20 years, they were unable to secure their own country, that we would take them to ours. That is nonsense. That has never been US government policy," Miller said.

Insider has reached out to Trump's office and Troye for comment. Stephen Miller could not immediately be reached for comment.