BEIRUT — Eight American citizens taken into Kurdish custody in northeastern Syria during the fight against the Islamic State have been repatriated to the United States, America's Syrian Kurdish allies said on Wednesday.

The eight include two women and six children and they were sent back "without any pressure or coercion" after the U.S. authorities submitted a request for their return, according to a statement issued by the Kurdish-led civilian administration in northeastern Syria.

The statement did not identify the Americans or say how they came to be in Syria, but officials had earlier said the eight were among around 13,000 foreigners, including around 8,000 children and 4,000 women, who had volunteered to join the Islamic State. They are all now being detained in prisonlike camps following the territorial defeat of the militants in March, according to figures supplied by the Kurdish authorities.

The transfers are the first publicly announced repatriations of U.S. citizens since the Islamic State war resulted in the capture or detention of many of the tens of thousands of foreigners who had flocked to join the group as it seized territory across Syria and Iraq earlier this decade. A small number have been sent back to the United States to face terrorism charges.

However, only a few dozen U.S. citizens are believed to have traveled to join the militants, according to counterterrorism analysts, making the United States one of the smallest contributors to the Islamic State's strength compared to other nations. A fraction of those known to have volunteered have been detained by the Kurds, including two Americans, Hoda Muthana, from Alabama, and Kimberly Gwen Polman, a dual U.S.-Canadian citizen, who were interviewed by the New York Times in Syria in February.

It was not immediately clear whether they were the two American women who were freed and the Kurdish authorities would not say whether any other Americans are still being held.

The transfer followed tweets by President Donald Trump in February and March urging European governments to "take back" and prosecute their citizens and criticizing Britain, France and Germany for refusing to do so. He did not mention the small number of Americans in Kurdish custody

Most Western governments have been reluctant to repatriate their citizens - including, until now, the United States - for a variety of reasons, including the fears that they will pose a security threat, pressure from constituents who don't want them living in their communities and the logistical challenges of reaching the remote area of northeast Syria where they are held.

The Kurdish authorities are however pressing foreign governments to take them back, saying they also pose a danger in northeastern Syria, where Kurdish forces lack the capacity to care for them indefinitely. In one camp alone, al-Hawl, 3,200 foreign women and 7,900 foreign children are being held alongside over 60,000 Syrians and Iraqis, according to figures provided by the Kurdish authorities.

Abdulkarim Omar, who heads the foreign relations department of the civilian authority established in northeastern Syria, said hundreds more are detained in two smaller camps.

There are also around 1,000 foreign male fighters held in prisons run by the Kurdish authorities, who are seeking international funding to bring them to trial in the self-proclaimed autonomous Kurdish region, he said.

But the authorities want to send the women and children back to their countries. There is a risk that they could escape, he said, and the Kurds don't have the resources either to guard, feed and house them long-term or to try to rehabilitate them so that they can be released.

Many of the 7,900 foreign children being held at the Al-Hawl camp have been inculcated with Islamic State ideology, making them "ticking time bombs," he believed.

"Taking them back could be dangerous and that's why the foreign governments want them to stay here," he said in an interview last week in the northeastern Syrian town of Qamishli, ahead of the release of the Americans. "But keeping them here is also a big mistake."

Kurdish officials said the U.S. military, which maintains a small number of troops in northeast Syria, helped facilitate the transfer of the Americans. The U.S. military declined to comment.

