The shooting of two National Guard members, one of whom later died, in Washington DC has led to major immigration policy changes by the Trump administration.

The Department of Homeland Security (DHS) has said the suspect – from Afghanistan – had entered the United States under an Afghan resettlement scheme launched during the Biden administration.

And Republican officials have claimed, without providing evidence, that he had not been vetted.

The DHS has suspended processing all immigration requests relating to Afghan nationals “pending further review of security and vetting protocols”.

The DHS said the suspect, 29-year-old Rahmanullah Lakanwal, entered the US under an Afghan resettlement scheme, Operation Allies Welcome (OAW).

The scheme was launched in August 2021 under the Biden administration to resettle “vulnerable” Afghans after the Taliban takeover of Afghanistan in the same year.

“They came in, they were unvetted, they were unchecked”, said President Trump, who called a reporter “stupid” for asking why he blamed the Biden administration for the Washington attack.

In an FBI news conference, the agency’s director Kash Patel claimed the previous administration “made the decision to allow thousands of people into this country without doing a single piece of background checking or vetting”.

And in a press release on the day of the attack, the DHS said the suspect “is one of thousands of unvetted Afghan nationals let into the country under the Biden administration’s Operation Allies Welcome program”.

On X this week, Vice President JD Vance recalled comments he made in 2021 “criticizing the Biden policy of opening the floodgate to unvetted Afghan refugees”.

He made similar remarks about vetting failures in an interview with CBS earlier this year. Vance highlighted the case of an Afghan national, also evacuated to the US after the Taliban takeover, who was later charged with terrorism-related offences.

Lakanwal entered the US through OAW on 8 September 2021, shortly after the fall of Kabul.

Many Afghans faced a serious risk of persecution by the Taliban, particularly those who had worked with Western governments.

More than 190,000 Afghans have been resettled under OAW and another programme called Enduring Welcome, according to a report published this year by the US State Department.

Most Afghan nationals arriving on the OAW programme were given permission to stay in the country for two years under a process known as “parole”.

Afghans on parole are subject to reporting requirements (such as medical screenings and critical vaccinations) and could lose their right to stay in the US if these requirements are not met.

Those who took “significant risks” to support US troops in Afghanistan were admitted as lawful permanent residents after completing the Special Immigrant Visa (SIV) process.

According to the charity AfghanEvac, Lakanwal had an active SIV application but was granted asylum this year under the current Trump administration.

We contacted the White House for more details about Lakanwal’s vetting. It did not provide them but told us:

“This animal would’ve never been here if not for Joe Biden’s dangerous policies which allowed countless unvetted criminals to invade our country and harm the American people.

“The Trump Administration is taking every measure possible – in the face of unrelenting Democrat opposition – to get these monsters out of our country and clean up the mess made by the Biden Administration.”

We also contacted the DHS and CIA, who did not get back to us.

Although we do not know the suspect’s vetting arrangements before he entered the US we do know how vetting was supposed to work for the scheme he arrived on.

An archived government website for the OAW scheme, last updated at the start of this year, mentions a “rigorous” and “multi-layered” vetting process, which involved collecting biometric information such as fingerprints and photos from Afghans before they were allowed to enter the country.

It mentions multiple government agencies involved in vetting, including the FBI and the National Counterterrorism Center.

The then Secretary of Homeland Security, Alejandro Mayorkas, said in 2021 that the government had “established a robust screening and vetting architecture” under the scheme.

There have been mixed reports into the effectiveness of the programme’s vetting.

A 2022 audit carried out by the Office of Inspector General (OIG) – a US government oversight body – found that “some information used to vet evacuees through US Government databases (such as name, date of birth, identification number, and travel document data) was inaccurate, incomplete, or missing”.

The OIG said this problem was partly as a result of the DHS not having a list of Afghan evacuees “who lacked sufficient identification documents”.

It also reported that US Customs and Border Protection (CBP) “admitted or paroled evacuees who were not fully vetted into the United States”.

Two years later another OIG audit of the scheme found weaknesses in the government’s ability to identify potentially negative information (such as national security concerns) about some Afghans parolees.

However, earlier this year the OIG commended the FBI for its role in screening Afghans on the scheme.

“Overall we found that each of the responsible elements of the FBI effectively communicated and addressed any potential national security risks identified,” it said.

As well as reviewing audits of OAW, BBC Verify contacted several experts for their views on the vetting process.

Alex Nowrasteh, an immigration analyst at the Cato Institute think tank, said the programme “was more inconsistent than usual by OIG accounts and compared to the more intensive refugee review process”.

“Because of the chaotic nature of the evacuation, information was lost and some checks weren’t run until the migrants were already out of Afghanistan.”

Jennie Murray, President and CEO of the immigration advocacy group the National Immigration Forum, told BBC Verify she was present at the US military bases where evacuees were initially processed.

“Evacuees were processed on military bases and held for several weeks, and even months, until they were ready for entrance into the United States. This is when the security vetting and medical screening was processed, extensively”, she said.

“Even the best vetting can’t predict the future. He [Lakanwal] could have had a clean record, been an appropriate candidate for humanitarian protection, and then something changed.”

In the four years since the evacuation, thousands of Afghans have safely resettled in the US and this is the first major incident, Ms Murray said.

“The fact that one person committed a horrific act doesn’t mean other Afghans now pose a threat,” she added.

CIA Director John Ratcliffe told CBS News, the BBC’s US partner, that the suspect had worked with the CIA in Afghanistan.

The BBC’s Afghan Service spoke to a soldier from Lakanwal’s former military unit, the Kandahar Strike Force (KSF).

The soldier said there was vetting to get into the unit which took around three to four weeks and involved being recommended by a senior KSF officer and undertaking a “call history check” of their mobile device.

If the candidate passed that stage they may have been referred to a security check carried out by the US, which involved collecting biometric data from the applicant.

The Afghan Service corroborated the soldier’s account by speaking to a commander from the KSF unit, who also confirmed the soldier’s identity and added that a criminal record check was also part of the vetting process.