Firefighters try to put out the fire in an oil tank in the port of Es Sider, in Ras Lanuf, Libya.

The United States and its allies are probably many weeks or even months away from launching a new military campaign against ISIS in Libya, despite mounting concern about the group’s spread there and its attacks on oil infrastructure, U.S. officials say.

The Pentagon has warned in recent weeks of the dangers posed by ISIS’ growth in Libya. The U.S. is developing military options, which were discussed at an inconclusive meeting last week of President Barack Obama and his top security aides, officials said.

Those options include increased air strikes, deploying U.S. special operations forces and training Libyan security forces, officials say.

But the U.S. officials, who spoke on condition of anonymity, said enormous hurdles stand in the way of increased American military involvement. The largest is the formation of a unified Libyan government strong enough to call for and accommodate foreign military assistance.

Getting some allies on board could also require a new mandate from the United Nations, they said.

“We’re not there yet,” said one U.S. official. He and other officials with knowledge of internal deliberations cautioned that it is too soon to estimate when military action might begin, but cautioned it could take many weeks or even months.

“As far as I’m aware, there is no clear intention to go ahead with the military-style action. There is a lot of thinking, a lot of thinking, a lot of planning,” said a Western diplomat.

U.S. and European officials describe Islamic State’s presence in Libya as increasingly worrisome, although not on the scale of its rule over swaths of Iraq and Syria.

ISIS forces have attacked Libya’s oil infrastructure and taken control of the city of Sirte, exploiting a power vacuum in the North African country where two rival governments have been battling for supremacy.

Estimates of ISIS fighters in Libya range from 3,000 to 5,000-6,000. Officials openly worry that the group could use its Libya haven to relieve the pressure from U.S. air strikes and local forces against its home base in Iraq and Syria.

Related articles across the web

• Einsteinian insanity: momentum grows to bomb Libya again
• War Against ISIS Poised To Expand Into Libya?
• The Plan Is Coming Along Perfectly
• Islamic State Found Weaker In Iraq, Syria, Stronger In Libya
• US Estimates: Up to 6,000 ISIS Fighters in Libya
• Libya Winning Race for Site of Obama's Next War?
• Libyan Lessons for Europe
• Obama Readies to Fight in Libya - Again
• More Flee Libya as Threat of Intervention Draws Near
• Can Libya survive yet more US assistance?