Iraq's Prime Minister Mohammed Shia Al Sudani met President Joe Biden at the White House on Monday amid soaring tension in the Middle East, following Iran's attack on Israel.
“Our partnership is pivotal for our nations, the Middle East and the world,” Mr Biden said from the Oval Office.
Mr Al Sudani said the visit comes at a "sensitive time".
“The relationship between the United States and Iraq is at an important juncture,” he said.
“We aim to discuss the sustainable foundations for a 360-degree strategic partnership."
Mr Al Sudani said it was vital to ensure "a smooth transition from a military security-based relationship to a comprehensive economic, political, environmental, educational and security partnership according to the Strategic Framework Agreement".
"The two leaders reaffirmed their commitment to the enduring strategic partnership between Iraq and the United States and discussed their visions for comprehensive bilateral co-operation under the 2008 US-Iraq Strategic Framework Agreement," the White House said after the meeting.
"The President and Prime Minister agreed on the importance of working together to advance regional stability and reinforce and respect Iraqi sovereignty, stability and security."
The White House said the leaders discussed the sustained defeat of ISIS, energy, the environment, regional integration, political co-operation, the economy and finance, and security co-operation.
The week-long visit, Mr Al Sudani's first since taking office, was supposed to focus on expanding bilateral ties, new economic opportunities and the exit of US forces from Iraq.
The White House said the two leaders had agreed that "Iraq’s security forces must be able to ensure that ISIS can never again reconstitute inside Iraq to threaten the Iraqi people, the region, or the international community, including the United States".
But Iran's drone and missile attack on Israel on Saturday is likely to overshadow the visit.
Israel, the US, the UK and other allies shot down most of the drones and missiles.
Iran has said it considers its military action against Israel complete – provided Israel does not strike back.
“Together with our partners, we defeated that attack,” Mr Biden said from the Oval Office.
Tehran said the assault was in response to an April 1 missile attack by Israel on Iran's embassy compound in Damascus that killed two senior Iranian commanders and other officers.
Israeli air strike hits Iranian consulate in Syria – video
Mr Biden needs Mr Al Sudani to rein in Iran-backed armed groups that conducted scores of attacks on US troops in Iraq and Syria since the Israel-Gaza war began.
The attacks began in October, after the Hamas attacks on Israel and the subsequent Israeli invasion of Gaza, but ceased in February, although the Iran attack has caused concern about the potential widening of the conflict.
Mr Al Sudani said that "under the spirit of partnership, our views might be divergent about what’s happening in the region”.
But he said the Iraqi government is “very eager to stop this war which claimed the lives of thousands of civilians, including women and children".
Meanwhile, Mr Al Sudani wants to secure an agreement on the withdrawal of foreign troops from his country, a decade after they arrived in Iraq to fight ISIS. He also wants more US companies to set up shop in Iraq.
About 2,500 US troops remain in Iraq in an advise-and-assist capacity, and the two countries began talks in January about ending the international coalition.
Earlier on Monday, members of the Iraqi delegation met Secretary of State Antony Blinken, who said talks would focus on "on a half a dozen issues, including energy security, democracy and rule of law, climate, water".
"The American private sector remains very interested in engaging, investing and lending its expertise to Iraq," Mr Blinken said.
A joint statement said that "to allow Iraq to benefit from the US private sector's leading technology and expertise, the United States and Iraq announced the signing of new memoranda of understanding to capture and process flared gas and turn it into usable electricity for the Iraqi people".
Iraq relies on Iran for about a third of its energy needs, and Baghdad owes Tehran several billion dollars.
"President Biden applauded Iraq’s progress towards energy self-sufficiency, and the two leaders discussed Prime Minister Al Sudani’s interest in future opportunities for co-operation to ensure Iraq becomes self-sufficient by 2030, with help from US companies." the White House said.
Last month, the administration renewed a 120-day waiver that allows Iraq to circumvent sanctions to pay Iran for energy.
Mr Al Sudani met Defence Secretary Lloyd Austin later in the afternoon, during which they "affirmed the two nations' commitment to an enduring US-Iraq bilateral defense relationship and to a strong Iraq, capable of self-defence in support of a more stable and peaceful region".
"Addressing the strategic nature of the US-Iraq bilateral defence relationship and Iraq's role as leader in ensuring regional security, the Secretary and Prime Minister discussed efforts to modernise the ISF [Iraqi Security Forces], including Kurdish Peshmerga forces, and build their capabilities," a joint statement said.
The visit took place a week after a meeting of the the US-Iraq Higher Military Commission, a professional military-to-military dialogue aimed at planning the end of the international coalition and how the anti-ISIS coalition will evolve based on the level of threat from terror group and Iraqi forces' preparedness.
