Last Updated Nov 13, 2014 4:49 PM EST
BEIRUT -- In a recording released days after he was reported to be wounded in an airstrike, the leader of the Islamic State of Iraq and Syria (ISIS) purportedly said the U.S.-led coalition's campaign had failed and it would eventually have to send ground troops into battle.
Abu Bakr al-Baghdadi urged his followers to "explode the volcanoes of jihad everywhere," according to the 17-minute message posted online Thursday. The recording appeared authentic, matching previous ones from the group, though it has not been independently confirmed.
The statement surfaced four days after Iraqi officials said al-Baghdadi was wounded in an airstrike in Iraq. It was not clear when the recording was made, but there were references to events since the weekend - including pledges of allegiance to the IS group by militants in Libya and Egypt.
It also was unclear why the message was only an audio recording. Al-Baghdadi has made only one public appearance since declaring himself caliph, delivering a sermon at a mosque sermon in June in the Iraqi city of Mosul. An earlier audio recording from him is believed to have inspired militants in Algeria to behead a French national.
The latest recording was his first since the U.S. and other partners in the alliance began an air campaign against the extremist fighters in both Iraq and Syria. Other messages from the group, including videos of U.S. and British captives being beheaded by the group, have shown other speakers.
Meanwhile, a high-level Syrian opposition official and a rebel commander have told The Associated Press that militant leaders from ISIS and al Qaeda gathered at a farm house in northern Syria last week and agreed on a plan to stop fighting each other and work together against their opponents.
Such an accord could present new difficulties for Washington's strategy against ISIS. While warplanes from a U.S.-led coalition strike militants from the air, the Obama administration has counted on arming "moderate" rebel factions to push them back on the ground. Those rebels, already considered relatively weak and disorganized, would face far stronger opposition if the two heavy-hitting militant groups now are working together.
In Washington, U.S. Army Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, told Congress on Thursday that the United States would consider dispatching a modest number of American forces to fight with Iraqi troops as they engage in more complex missions in the campaign against ISIS militants.
"I'm not predicting at this point that I would recommend that those forces in Mosul and along the border would need to be accompanied by U.S. forces, but we're certainly considering it," Dempsey told the House Armed Services Committee.
Defense Secretary Chuck Hagel said the coalition had made progress against the militants since beginning its efforts in September.
"ISIL's advance in parts of Iraq has stalled, and in some cases been reversed, by Iraqi, Kurdish, and tribal forces supported by U.S. and coalition airstrikes," Hagel said in testimony to the House Armed Services Committee, using another acronym for ISIS. "But ISIL continues to represent a serious threat to American interests, our allies, and the Middle East ... and wields influence over a broad swath of territory in western and northern Iraq and eastern Syria."
CBS News correspondent Elizabeth Palmer reported that the U.S.-led airstrikes have slowed the militants' speedy advance and helped Kurdish peshmerga soldiers in the north hold their ground.
In the town of Kobani, they even pushed ISIS back, but that was an exception.
In spite of the U.S. military spending an average of $8.3 million a day on this operation, ISIS hasn't given up much -- if any -- territory. It still controls a huge wedge -- more than 10,000 square miles -- of Iraq and Syria, including major roads and border crossings.
The mostly Sunni extremists have seized large parts of Syria and Iraq. They later announced their proto-state straddling the two countries, where they have implemented a violent interpretation of Islamic law, including public beheadings, massacring rebellious tribes and selling women and children of religious minorities into slavery.
President Barack Obama had authorized the deployment of advisory teams and trainers to bolster struggling Iraqi forces. Obama's plan could boost the total number of American troops in Iraq to 3,100. There are about 1,400 U.S. troops there, out of the 1,600 previously authorized.
Al-Baghdadi said in his statement that the coalition effort had failed to repel his fighters.
"They thought and they estimated, they planned and they conspired, and they prepared to hit the Islamic State, and then they emerged with a failed plan that was to shell the sites of the Islamic State, and its brigades and its vehicles and its soldiers to halt its advance ... but quickly the failure of this plan was apparent," he said. "Soon the Jews and Crusaders will be forced to descend to earth, and to send its ground forces to its end and destruction, by God's will."
He pointed to the announcement of additional troops as proof the airstrikes were not working.
"And here is Obama, sending another 1,500 troops, claiming they are advisors, because the strikes of the Crusaders that continue night and day on the sites of the Islamic State have not halted its advance," al-Baghdadi said.
He urged Muslims to wage holy war everywhere, and to attack and kill "apostates" in Saudi Arabia and Yemen specifically. He also vowed that his group's advance would "reach Rome." Islamic militants often refer to Rome as a symbol of Europe.