Washington CNN  — 

Qatar, a key Arab partner in the U.S.-led coalition against ISIS, believes the coalition is not doing enough to fight the terror group, Qatari officials tell CNN.

In particular, these officials say the training of moderate rebels needs to be accelerated and expanded. To date, Qatar has trained some 600 fighters. Training is also underway in Saudi Arabia and Turkey. The U.S. is still in the process of vetting moderate rebel groups.

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Qatari officials, in Washington this week to meet President Barack Obama and lawmakers on Capitol Hill, believe the coalition also needs to expand the campaign to target the forces of Syrian President Bashar al Assad, a step the U.S. has refused to take despite an oft-stated policy of seeking the removal of Assad.

At a minimum , Qatari officials tell CNN, the U.S. and its allies should act to prevent Assad’s use of barrel bombs on civilians. Qatari officials believe that Obama’s failure to enforce his own red line following Syria’s use of chemical weapons was damaging to U.S. credibility in the region.

The U.S. has had its own disagreements with Qatar, in particular, accusing the Persian Gulf state of providing financial support to extremists in Syria and allowing Qatari individuals and organizations to funnel money to some of the most extreme groups, including the al Qaeda-tied Nusra front.

More recently, U.S. and Arab officials have credited Qatar with reducing its support. However, in a meeting with the Qatari Amir Sheikh Tamim bin Hamad Al Thani on Wednesday, Treasury Secretary Jacob Lew continued to emphasize the vital importance of combating the financing of terrorism.

In addition, Qatar allows groups such as Hamas, which the U.S. designates a terrorist organization and the Muslim Brotherhood to keep offices in the Qatari capital Doha.

Qatari officials countered that Qatar is doing all it can to stop the flow of terror financing and that if the U.S. wants Qatar to go after particular bad actors, it should share the evidence with Qatar so it can investigate and arrest suspects, Qatari officials told CNN.