BRUSSELS: The United States is renewing pressure on its European Nato allies to establish a long-term train-and-advise mission in Iraq, diplomats said, reviving a divisive issue for an alliance wary after a decade in Afghanistan.

US Secretary of Defence Jim Mattis sent a letter to Nato headquarters in January calling for a formal Nato mission to Iraq with a semi-permanent or permanent command to train Iraqi forces, according to five senior Nato diplomats.

After a three-year war with Daesh, Washington wants to ensure the militants do not re-emerge. While Nato does have trainers in Iraq already, they number less than 20.

Nato defence ministers are expected to discuss the US request in Brussels next week, with a possible decision at a summit in July.

In his letter, Mattis left many details open but suggested developing military academies and a military doctrine for the Iraqi defence ministry, diplomats said. Other ideas cited by diplomats include bomb disposal training, maintenance of Soviet-era vehicles and medical training.

“The United States is pushing hard for a Nato role in Iraq, not in a combat role, but for a long-term assignment,” said one senior Nato diplomat on condition of anonymity.

“This looks suspiciously like another Afghanistan,” the diplomat said, referring to the long-running conflict where Nato is funding and training Afghan forces.

“Few allies want that.”

Pentagon spokesman Johnny Michael declined to discuss whether Mattis had sent a letter to Nato but said: “The administration continues to look for ways allies can do more to counter terrorist organisations.” A Nato official said that the alliance is “looking into how we can step-up our training efforts.”

Nato defence chiefs will provide ministers with a range of options for an Iraq mission, while Nato Secretary-General Jens Stoltenberg has discussed the issue with Prime Minister Haider Al Abadi, who supports a mission, diplomats said.

The US push is also part of President Donald Trump’s demand that the Western alliance go beyond its core task of defending its territory and help stem Islamic militancy.

Trump scolded allies last May at a summit in Brussels, warning of more attacks in Europe if Nato did not do more to stop militants. Even his predecessor Barack Obama sought a greater Nato role in the Middle East.