Officials in Iraq's third largest city warned that despite declining violence in the country, the U.S. must launch a widespread offensive on Syria if it expects to finish the job.

With conditions around Iraq drastically improved, Mosul has remained Al Qaeda's last stronghold despite efforts to secure the city with extra troops, The London Daily Telegraph reported.

One problem "is that the terrorists can come across the border … So the number of security forces is never enough to defeat the threat," Mosul Provincial Governor Dureid Kashmula told The Telegraph.

Vice Governor Khosro Goran agreed, telling the Telegraph, "We have an open border with Syria and our neighbors are actively encouraging the terrorists."

Those neighbors have managed to infiltrate security forces with terrorist sympathizers who are impossible to catch "because mostly they are based outside the city, even outside the country," Mosul police Captain Nabeel Mutlak told the Telegraph.

The turmoil even garnered an unprecedented apology from senior U.S. commander in northern Iraq Maj. Gen. Mark Hertling who told the city, "We have not supported you enough. We have focused too much on Baghdad," The Telegraph reported.

The American raid on a Syrian compound that was allegedly housing Al Qaeda operatives last month has triggered calls for more sweeps of its kind, the paper reported.

Baghdad launched a massive mobilization of troops, dubbed Operation Lion's Roar, to secure the city six months ago but gains have been tenuous, the Telegraph reported.

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