Congress is urging the administration of US President Joe Biden to enhance engagement with Iraq and the Kurdistan Regional Government over "a range" of ongoing disputes, while condemning Iran's "blatant violations of Iraqi sovereignty".
Iraq and the Kurdistan Regional Government's escalating disputes over natural resources have threatened Washington's investment in "supporting a stable, sovereign and democratic Iraq free from malign foreign influence", Michael McCaul, Republican leader of the House Foreign Affairs Committee, said in a letter to Secretary of State Antony Blinken.
The natural resources dispute has been exacerbated by infighting among Iraq's political parties, which have failed to form a government since elections in October last year.
"Meanwhile, the Iraqi people suffer, lacking a government that represents their interests and unable to reap the full benefits of revenues from Iraq’s oil, gas and other natural resources," Mr McCaul wrote.
Mr McCaul also called for a "robust" administrative response to Iran's actions in the region, condemning recent missile attacks from Tehran as "blatant violations" of Iraq's sovereignty. In an unprecedented assault in March, Iran attacked the Kurdish regional capital Erbil, appearing to target the US and its allies.
Adding to the sense of instability, anger in Iraq has continued to fester after Baghdad accused Washington's Nato ally Turkey of being behind a July attack in the Kurdish district of Zakho that killed at least nine people.
Mr McCaul's letter on Monday highlighted the more than $12.7 billion in foreign, security and humanitarian aid Washington has sent to Iraq since 2014.
"These investments of taxpayer dollars must be accompanied by a commensurate diplomatic push to urge Iraq’s leaders in Baghdad and Erbil to negotiate with each other and make the political decisions necessary to protect Iraq’s sovereignty and prosperity to benefit the Iraqi people," Mr McCaul wrote.
The minority leader sent the letter weeks after the US embassy in Baghdad expressed concern over the Kurdish government using violence against demonstrators protesting against unpaid state salaries as well as Turkish incursions into border areas.
Non-profit organisation the World Resource Institute's Fragile State Index ranks Iraq as "extremely vulnerable" to collapse, with a score of 100 out of 120.