US President Donald Trump repeats call for more restrictions on immigration policies following arrest of suspect of Bangladeshi origin.

Commuters exit a train as police officers stand in a closed-off underground walkway near the site of a pipe bomb explosion in the tunnel that connects the Times Square subway station to the Port Authority Bus Terminal on December 11, 2017 in New York City.
Commuters exit a train as police officers stand in a closed-off underground walkway near the site of a pipe bomb explosion in the tunnel that connects the Times Square subway station to the Port Authority Bus Terminal on December 11, 2017 in New York City. (AFP)

The arrest of a Bangladeshi immigrant accused of making a homemade pipe bomb and setting it off in the New York subway system on Monday has led to discussion of the nation's immigration system, with President Donald Trump repeating his refrain that it needs to be overhauled in favour of more restrictions. 

Here's what you need to know:

How did the suspect arrive in the US? 

Authorities say the bombing suspect, 27-year-old Akayed Ullah and originally from Bangladesh, arrived in the United States in 2011 and was living in Brooklyn. The Department of Homeland Security says he's a lawful permanent resident of the US.

Ullah came to the US on an F43 visa, issued to him through his family connection to an American citizen. The American immigration system allows citizens to apply for certain relatives – spouses, children, parents, siblings and their spouses and minor children – to be allowed to come and live in the US. The visas fall under different preferences, or categories; siblings of US citizens come in the fourth preference, the F4, and their children come under F43s.

How did US immigration policy change?

Since a law change in 1965 loosened what had been a very restrictive system, America's immigration policy has been based around giving preference to people with advanced education or skills or those with family ties to US citizens. What that has meant is that as immigrants from places like Asia and Latin America started coming to the US in larger numbers and became citizens, they applied for their family members to join them. Once naturalised, those brought in were able to then sponsor their own relatives.

How does the proposed RAISE Act plug this kind of migration?

US Senators Tom Cotton and David Perdue, both Republicans, have most recently proposed the Reforming American Immigration for Strong Employment Act (RAISE Act), which would limit the number of permanent-resident visas and do away with the ability of citizens to bring over relatives other than spouses and minor children. Immigrant advocates have called the bill an attack on immigrants.

Trump, a Republican, has voiced his support of the RAISE Act.

Has the incident offered Trump, who’s known for his anti-immigration policies, a shot in the arm?  

Yes. Trump has made immigration a centerpiece of his presidency, in the form of banning residents from certain countries from traveling to the US, calling for the construction of a wall along the Mexican border and limiting the number of refugees allowed in.

The New York incident gave him yet another opportunity to target US' immigration rules.

After the subway explosion, Trump issued a statement saying, "America must fix its lax immigration system, which allows far too many dangerous, inadequately vetted people to access our country. Today's terror suspect entered our country through extended-family chain migration, which is incompatible with national security."

Source: AP