
Islamic State (ISIS) fighters have in recent months been moving from Iraq and Syria into Libya, an American official said Thursday, heightening fears that the extremists are gaining ground and influence in the north African country.
About 5,000 ISIS jihadists are now in Libya, the defense official said, according to AFP. That number is approximately double earlier estimates, while the number of ISIS extremists in Iraq and Syria has dropped.
The updated tallies comes as the administration of President Barack Obama faces growing calls for the United States military to step up action against ISIS in Libya, where the jihadists have already seized the city of Sirte and an adjoining length of Mediterranean coastline.
Recent reports said ISIS terrorists in Sirte are learning to fly planes using at least one flight simulator according to military officials in the strategically situated North African state.
These reports are concerning, given that Libya is located on the Mediterranean Sea and provides a strategic point of transit to Europe.
NATO defense ministers are meeting in Brussels next week to evaluate the ongoing U.S.-led coalition campaign against ISIS and to discuss ways of redoubling efforts, according to AFP.
The United States now believes there to be between 19,000 and 25,000 ISIS fighters in Iraq and Syria -- the group's so-called "caliphate" -- down from a previous count of 20,000-33,000.
But there are growing fears about the fate of Libya, which has been in chaos since the NATO-backed ouster of longtime dictator Muammar Qaddafi in 2011.
ISIS has capitalized on the disarray and spread the group's influence into the north African nation, establishing a stronghold in Sirte, Qaddafi’s hometown.
ISIS's presence in Libya made headlines a year ago when it broadcast the brutal mass execution of 21 Coptic Christians, triggering reprisal air raids from Egypt and a mass-exodus of Egyptian workers from the country.
Also in 2015, ISIS terrorists published a video in which they vowed that their conquest in Libya will serve as a springboard for a European invasion.
According to AFP, life in Sirte, which ISIS fighters seized in June, now resembles that of other towns flying the jihadists' signature black flag. Witnesses have described public executions and say women are no longer allowed outside without a male guardian.
Reluctant to see its 18-month air campaign against ISIS in Iraq and Syria spread to a third country, the United States has repeatedly stressed the importance of finding cooperative local partners to help fight the IS group in Libya.
Washington has also pushed international allies -- especially former colonial power Italy -- to take the lead in any coalition operations there.
And administration officials say any actions in Libya must be carried out in the context of a functioning government.
While Obama is not considering opening "a new front" against the IS group in Libya, White House spokesman Josh Earnest said this week the United States is ready to intervene if necessary.
"We're going to continue to watch how the threat in Libya evolves and we're going to continue to be prepared to take action," he said.
The United States has already taken some limited steps in Libya. In November, it launched an air strike killing top ISIS leader Abu Nabil, an Iraqi also known as Wissam Najm Abd Zayd al-Zubaydi.
And in December the Pentagon acknowledged that a group of U.S. special operations troops who traveled to Libya to "foster relationships" was kicked out of the conflict-torn country soon after arriving.
AFP contributed to this report.