UNITED NATIONS (AP) — The United States is hoping for unanimous approval of a U.N. resolution calling for global action against the growing phenomenon of foreigners traveling to fight for terrorist groups when President Barack Obama hosts a Security Council summit later this month, U.S. Ambassador Samantha Power said Wednesday.

Power told reporters that foreign fighters like those in Iraq and Syria participate in "brutal atrocities" and often return home radicalized by their experiences, "posing threats of the most profound kind to their fellow citizens."

She said the resolution the U.S. is drafting is aimed at strengthening the ability of governments to curb the flow of their citizens to war zones. It calls for improved information and intelligence sharing, and will also underscore the importance of countering violent extremism through programs that would give would-be fighters alternatives to violence, she said.

The United States holds the Security Council presidency this month. As the centerpiece of the U.S. term, Obama has invited leaders of the 14 other council nations to a summit on Sept. 25 to address the threat posed by foreign fighters, whose terrorist actions have been gaining momentum with the recent offensive by the group calling itself the Islamic State, which has taken control of a large swath of eastern Syria and northern and western Iraq and beheaded two American journalists in the past two weeks.

A U.S. official said last month that an estimated 12,000 foreign terrorist fighters have taken up arms in Syria and Iraq.

The Security Council responded to the growing terrorist threat in the two countries by unanimously adopting a resolution on Aug. 15 imposing sanctions on six men from the Islamic State group and the al-Qaida-linked group Jabhat al-Nusra for recruiting or financing foreign fighters, and threatened additional sanctions.

If approved, Power said the resolution the U.S. is currently drafting would be the first focusing on foreign terrorist fighters.

She said there is consensus in the council about "the gravity of the threat" and the fact that the repercussions can touch any country.

If the resolution is approved, "a huge amount of hard work" will be required by countries to curb the flow of fighters, tackle their financing and counter violent extremism, she said.

The United States, in response to a request from the Iraqi government, has been providing air support to Iraqi and Kurdish fighters trying to oust the Islamic State group, previously known as ISIL or ISIS.

Power was pressed several times about what the United States was going to do about the group's fighters in Syria.

"There's no question that ISIL has enjoyed a safe haven in Syria that has allowed it to amass the kind of weaponry and resources that it then was able to bring to bear in Iraq," she said. "I think the question of Syria, and how the ISIL phenomenon gets dealt with in Syria, is one that is being considered at the very highest levels in a very urgent manner."