President Donald Trump’s secretaries of state and defence told Congress he has all the authority he needs to fight terrorism with US forces from Niger to Syria, after lawmakers from both parties raised concern about the extent of military deployments.

In testimony Monday before the Senate Foreign Relations Committee, Secretary of State Rex Tillerson and Pentagon chief Jim Mattis said long-standing authorisations for the use of military force — passed after the 2001 terrorist attacks to combat Al Qaida and its affiliates — are sufficient to continue the US fight against groups such as Daesh that have emerged since then.

But Maryland Senator Ben Cardin, the top Democrat on the committee, pushed back, saying that with US forces in hostile environments in 19 nations, a new or revised AUMF is needed. The fight over the authorisation has heated up after the deaths of four US soldiers in an ambush this month in Niger. Lawmakers have said they haven’t been kept informed of US deployments and haven’t received enough information about what happened in Niger.

“There needs to be more public discussion and light on these activities because I do not think the American people want the United States conducting a global, endless shadow war under the radar, covert and beyond scrutiny,” Cardin said in his opening statement.

While Tillerson and Mattis both defended the current war authorisations, they said any new measure from Congress shouldn’t impose deadlines or geographic restrictions.

“Legislation which would arbitrarily terminate the authorisation to use force would be inconsistent with a conditions-based approach, and could unintentionally embolden our enemies with the goal of outlasting us,” Tillerson said.

Under questioning from Cardin about the Niger attack, Mattis said US troops had been deployed there “in a train-and-advise role” and weren’t there under the authorisations for the use of force.

“The mission of those troops on that patrol was a combined patrol which means they were with Niger troops,” Mattis said.