Secretary of Defense James Mattis told the Senate Appropriations Committee that American troops should remain in Iraq even after the Islamic State is defeated.

“I don’t see any reason to pull out again, and find the same lesson,” said Mattis during a hearing on Wednesday.

“I believe it’s in our national interest that we keep the Iraqi Security Forces in a position to keep our enemies on their back foot, our mutual enemies on their back foot,” he added, saying he expected the Iraqi military to need U.S. support for “some time to come.”

Joint Chiefs chairman General Joseph Dunford, appearing with Mattis, clarified that the Iraqis would need additional support for several years.

“We need to remain decisively engaged in Iraq and in the region,” the Defense Secretary said.

The Washington Examiner reports that when Senator Lindsey Graham (R-SC) asked Mattis about the estimated $50 billion reconstruction cost for Anbar province and Mosul, Mattis replied, “It’s going to be an international effort. It should not be carried fully by the U.S. taxpayer.”

Military Times notes that Mattis made his remarks as “the U.S. military campaign approaches its three-year anniversary, building from airstrikes against the terrorist group in summer 2014 to about 6,000 ground forces currently deployed across Iraq and Syria.” Another 2,500 troops are on deck in Kuwait as possible reinforcements.

Mattis is asking Congress for $30 billion in additional military funding, including $5 billion for anti-ISIS operations, to “get our aircraft back in the air, our ships back to sea, and our troops back in the field with refurbished or new equipment and proper training,” as he put it. He described this as a “necessary investment to ensure our military is ready to fight today.”

Mattis also attended a meeting with Iraq’s Prime Minister Haider al-Abadi and representatives from partners in the 68-nation anti-ISIS coalition on Wednesday, co-hosted by Secretary of State Rex Tillerson. Strategies to both defeat the Islamic State and deal with humanitarian crises in the aftermath of Mosul’s recapture were on the agenda. Some coalition members have reportedly expressed concern that the Trump administration’s proposed reductions to foreign aid will make reconstruction in Iraq and Syria more difficult.

Secretary of State Tillerson has also said that American forces would remain in Iraq after the defeat of the Islamic State.

“The military power of the coalition will remain where this fraudulent caliphate has existed in order to set the conditions for a full recovery from the tyranny of ISIS,” Tillerson said on Wednesday. He stressed that U.S. forces would not be engaged in “nation-building” but would support efforts by local leaders to restore their communities and rejuvenate civil society.