Syrian refugees
Syrian refugeesFlash 90

The United States said it would welcome its 10,000th Syrian refugee of this fiscal year on Monday, meeting a controversial target more than a month ahead of schedule.

The United States has traditionally been by far the world's most generous host for refugees but has been criticized by activists for moving too slowly to respond to the Syrian crisis, which has dragged on for more than five years.

President Barack Obama's opponents, including Republican presidential nominee Donald Trump, meanwhile warn that Islamic State extremists could infiltrate the refugee ranks to gain entry to the United States.

"Our 10,000th Syrian refugee will arrive this afternoon," National Security Advisor Susan Rice said in a statement, adding that the administration had met the goal "more than a month ahead of schedule."

Rice said the number represented a "six-fold increase from the prior year," and called it "a meaningful step that we hope to build upon."

She noted that refugee admissions represented only "a small part of our broader humanitarian efforts in Syria and the region."

"On behalf of the president and his administration, I extend the warmest of welcomes to each and every one of our Syrian arrivals, as well as the many other refugees resettled this year from all over the world."

Frontline states like Lebanon and Jordan have been all but overwhelmed by Syrian refugees, with each home to hundreds of thousands of them, and the arrival of streams of unvetted migrants on Europe's shores provoked a crisis.

The Syrian refugees admitted to the United States are chosen from United Nations camps and then vetted by US security and intelligence agencies. They are classified as "vulnerable," such as widows, the elderly and disabled.

Overall, the United States will admit at least 85,000 refugees over the year, Rice said, mentioning that others would come from countries such as the Democratic Republic of Congo, Iraq, Myanmar and Somalia.