Leaders of foreign affairs, intelligence and armed services committees in the US Congress issued a statement on Monday warning against the withdrawal of American troops from Iraq.
The Pentagon is reviewing options for US President Donald Trump on American military presence in Syria and Iraq.
At the same time, the Iraqi Parliament is preparing to introduce two bills this week calling for withdrawal of all foreign troops from the country.
“The United States must remain committed to supporting a sovereign and democratic Iraq,” the US Congress statement read.
“At the request of the Iraqi government, American trainers and advisers have helped to lay the groundwork for a safe, democratic Iraq, including the training of more than 89,000 soldiers of the Iraqi Army and the Regional Guard Brigades.
"But we need to make sure this stability is sustainable."
The leaders urged the Trump administration to continue joint training and humanitarian work in Iraq after ISIS territory has been liberated.
They also asked for closer co-ordination with international charity organisations and partners including the United Nations, European allies and Arabian Gulf countries in the process.
French Defence Minister Florence Parly is visiting Washington this week.
“At this critical point, it would be a mistake to pull back from Iraq as it seeks to preserve its sovereignty from both internal and external threats and grow into a thriving, vibrant democracy,” said the statement, signed by Democrat and Republican committee leaders.
Mr Trump was seeking a full withdrawal from Syria but the administration is now talking about a "draw down" and a "residual force".
The Wall Street Journal reported on Sunday that the US could leave 1,000 troops in Syria. Diplomatic sources told The National that this number will be higher than 400 and close to 1,000.
But US commander General Joseph Dunford denied the report.
"There has been no change to the plan announced in February and we continue to implement the president's direction to draw down US forces to a residual presence,” Gen Dunford said.
Mr Trump, however, in December called for a full withdrawal from Syria.
There are fears in congress and the Pentagon that he would do the same in Iraq, especially if the US presence there came under more political pressure from Baghdad and neighbouring Iran.
The Iraqi Sairoon and Fatah political blocs have drafted two bills that call for an end to foreign troop presence in Iraq.
On Monday, in a meeting in Damascus of defence chiefs from Iran, Iraq and Syria, called for the US to withdraw from Syrian territory.
The US has about 2,000 troops in Syria and 5,000 in Iraq.
Also on Monday, US Vice President Mike Pence spoke on the phone with Iraqi Prime Minister Adel Abdul Mahdi to reaffirm their partnership.