The recent video of Islamic State terror leader Abu Bakr al-Baghdadi reasserting his presence was a jarring reminder of a grim reality: The battle against terror, in Iraq and Syria and worldwide, is evolving – not over. Contrary to some public perception, ISIS is not defeated and the threat could again intensify if left unchecked.

Moving forward, it is vital that America’s resolve and commitment to the Iraqi people remain strong. Iraq has the potential of establishing itself as a self-sustaining, sovereign nation that can be a positive center of gravity in that region – an outcome that is strongly in our interests, as Iraq is one of our key strategic partners in the Middle East. Through continued work and thoughtful strategy, we can help them withstand internal and external pressures that could otherwise force them off this path.

This was the top takeaway we were given by numerous officials and men and women in uniform when we traveled to Iraq as part of a congressional delegation last month. There is an old saying: “One day of seeing is worth 30 days of reading.” With that in mind, the three of us went to Baghdad, Taji and Erbil, to see, listen and learn. What we heard from all levels was the same message: ISIS is still an active, present and dangerous terrorist and insurgent threat that must not be allowed to regain a foothold in the region.

To be sure, the American-led alliance in partnership with the Iraqis has made important and impactful strides in the battle to destroy ISIS, including reclaiming land that had previously been part of the Islamic State’s caliphate. However, defeating ISIS’s caliphate has not eliminated all of their fighters – which estimates place in the tens of thousands between Iraq and Syria – or eliminated the influence of their ideology on the region. Many ISIS fighters have moved underground and dispersed geographically, adopting the playbook of insurgents and terror organizations like al-Qaida, while others congregate in displaced persons camps.

Though ISIS was the overriding concern expressed to us during our congressional delegation, it is far from the only threat to Iraq’s long-term independence and security. In particular, the brooding omnipresence of neighboring Iran, including the destabilizing presence of Iran-backed militias in the Iraqi security forces, looms large over Iraq’s future. If we are to ensure that Iraq remains one of our close strategic partners in the region, and emerges as a truly independent nation, we need to make certain that Iranian influence is not predominant as Iraq works to strengthen its nascent democratic values.

Our conversations in Iraq emphasized the dangers of a power vacuum in the country – but fortunately, they also pointed to how we can prevent such a vacuum from forming. Even better, this solution doesn’t require a massive new investment of manpower or resources – but we do need to remain engaged with the Iraqi government and its people to save Iraq. Securing democratic norms, creating jobs, improving infrastructure: These are all end results in which we can play a lasting role.

It is also incredibly important that Americans know we are not in this fight alone. As we met with American service members in the mess hall food lines, we stood side by side with allies and partners from Sweden, Canada, and more – members of a coalition of 79 nations fighting against ISIS in the region. By continuing to lead this coalition, we can keep ISIS from reclaiming the territory it recently held, and continue to battle insurgents and terrorists who seek to destabilize the region and harm our people.

We’ve made significant progress in Iraq – but at the same time, these advances are fragile and Iraq is at a precipice. For the sake of the people of Iraq, of America, of the world, we cannot leave this work unfinished. This is a vital moment in the history of our relations with Iraq – a moment that calls for steady American leadership. We are certain that our diplomats and service members are up to the task, and we intend to make sure that our colleagues in Congress are aware of the importance of this mission as well.