The global coalition to ensure the defeat of the Islamic State terror group is set to wind down its military mission in Iraq, part of a two-phased plan that U.S. officials say will not hinder counter-IS operations elsewhere in the region.

Deputy Pentagon press secretary Sabrina Singh told reporters Friday that the mission would be changing to a bilateral security partnership with the Iraqi government.

"The U.S. is not withdrawing from Iraq," Singh told reporters in response to a VOA question at the briefing. "I cannot get into more details on what that front footprint is going to look like."

The first phase of the agreement, set to start immediately, will see coalition forces wrap up their efforts in Iraq no later than a year from now, senior U.S. officials said Friday.

The second phase, they said, will start next September and will last at least one year, allowing a remnant of coalition forces to remain in Iraq for the sole purpose of supporting anti-IS efforts in neighboring Syria.

The U.S. officials, who briefed reporters on the condition of anonymity, declined to say what impact the two-phased agreement would have on the 2,500 U.S. forces in Iraq and the 900 troops in Syria, but, like Singh, rejected characterizations of the agreement as a U.S. pullout.

"This is an evolution of the military mission in Iraq," the official added. "We are moving toward the type of productive, long-term security relationship the United States has with partners around the world."

Other officials said that despite a broad agreement on ending the coalition's military role in Iraq, key details have yet to be decided.

The number of U.S troops in Iraq and the fate of U.S. bases "remains in a planning process and under review," said a senior U.S. defense official, emphasizing that no matter what changes are ultimately implemented in the first phase of the transition, it will not adversely affect support for U.S. forces helping to counter IS in Syria.

"Our footprint is going to be changing," said Pentagon Deputy Press Secretary Sabrina Singh, briefing reporters Friday.

She said the U.S. relationship with Iraq remains crucial, however, even if the threat from IS in Iraq is not as dire as it once was.

"The strongholds that they had in Iraq, they don't have those anymore, or not what they used to," she said in response to a question from VOA.

Friday's long-awaited announcement comes 10 years after the U.S. and dozens of other countries joined forces to help roll back IS' self-declared caliphate, which at its peak covered nearly one-third of Iraq and Syria.

It also comes more than a year after the U.S. and Iraq first proposed talks to wind down the counter-IS mission and following rocket and drone attacks on U.S. troops, including by Iraqi militias backed by Iran.

The U.S. officials said under the transition agreement, the Iraqi government will remain responsible for protecting U.S. and coalition forces from attacks from Iranian-backed militias, though that will not stop U.S. forces from responding.

"We've made it clear also that [the U.S.] will not hesitate to take all appropriate actions to protect our personnel," said the senior administration official. "Attacks against the U.S. and the coalition service members, as well as Iraqi security service members, undermine Iraq's sovereignty and security and stability."

Some public statements from Iraqi officials, including Iraqi Defense Minister Thabit al-Abbasi, have stressed that the deal would see most of the U.S. troops in Iraq leave within the next two years.

In an interview with Al-Hadath television earlier this month, al-Abbasi said U.S. Defense Secretary Lloyd Austin had pushed for a longer transition period, but that Iraq said no.

"We refused his proposal regarding a third year," said Abbasi.

U.S. officials said they view the agreement to end the coalition military mission in Iraq not as an end, but a transition to a potentially stronger relationship with Baghdad.

"The government of Iraq has expressed continual willingness and interest to solidify and expand that partnership, including on counterterrorism cooperation," said the senior U.S. defense official. "We're very confident that we have a good partner in Iraq, in the government of Iraq."

The defense official also said the two-phase agreement to end the coalition military mission does not preclude cooperation between U.S. and Iraqi security forces against IS, like a joint operation earlier this month which killed a senior IS commander in Iraq's western Anbar province.

Iraqi Prime Minister Mohammed Shia al-Sudani also seemed to leave open the possibility of continued cooperation with U.S. forces despite a desire for counter-IS coalition forces to leave.

"We celebrate the coalition," al-Sudani told a conference on the sidelines of the United Nations General Assembly in New York on Wednesday, adding, "this mission is finished."

"We hope we will have a wider relationship, a more profound relationship with the United States," he said. "It's a strategic relationship."

Singh called the United States' military partnership with Iraq "crucial."

"We are in Iraq at the invitation of the Iraqi government, and our partnership has led to the success of diminishing ISIS from what it was 10 years ago to where it is today," she told reporters Friday, using an acronym for the terror group.

Despite statements by Iraqi officials downplaying the need for coalition forces in Iraq to combat IS, some U.S. officials and independent analysts have expressed growing concern that the terror group is rebounding.

U.S. Central Command, which oversees U.S. forces across the Middle East, warned in July that IS in Iraq and Syria "was on pace to more than double the total number of attacks they claimed in 2023."

The warning noted that beyond reconstituting its operations in Iraq and Syria, IS officials appear to be expanding their efforts to plan and carry out attacks elsewhere in the world.

Charles Lister, the director of the Countering Terrorism and Extremism Program at the Middle East Institute, has tracked about 500 IS attacks this year and warned that an IS rebuild, years in the making, in the central Syrian desert has been flowing across the Euphrates River since January.

"That spillover across the river is now a very real reality," he said, pointing to a "huge surge" in Islamic State attacks in both Syrian regime-held areas and in areas held by U.S.-allied Syrian Democratic Forces.

"It's more than predictable that the next phase of this recovery will be a spillover into Iraq," Lister said.

A recent United Nations report, based on intelligence from member states, estimated IS has between 1,500 and 3,000 fighters in Iraq and Syria. It said the majority of the terror group's senior leaders remain in hiding in Syria.

U.S. intelligence officials have put the number of IS fighters in Iraq and Syria at about 2,500.

Some information from Agence France Presse was used in this article.