Top US officials are warning the Russian and Syrian governments against chemical weapons use in Syria as forces allied with Syrian President Bashar al-Assad prepare for an offensive on a rebel stronghold.
The United States "will respond to any verified chemical weapons use in Idlib or elsewhere in Syria in a swift and appropriate manner," State Department spokeswoman Heather Nauert told reporters in Washington during a briefing Wednesday.
Nauert said senior US officials engaged with their Russian counterparts "to make this point very clear to Damascus," adding that the use of chemical weapons "will not be tolerated."
CBN News and other reporters pressed Nauert on if intelligence officials are seeing activity on the ground.
All Nauert would say is the Syrian government is gearing up for an expected offensive in Idlib province, which is home to nearly 3 million people and has a large al Qaeda presence in addition to Syrian rebel groups.
In the past, President Donald Trump has twice carried out airstrikes in Syria in response to apparent chemical weapons attacks there.
The president warned Assad against launching chemical weapons attacks again.
At the Pentagon Tuesday, Defense Secretary Jim Mattis referred to those two airstrikes. However, he offered no further information on how the US was responding to the situation, other than to cite the State Department's "recent active communication with Russia to enlist them in preventing this."
In April, the United States, France and Britain launched military strikes in Syria to punish Assad for an apparent attack using chlorine against civilians in the Damascus suburb of Douma.
And in 2017, Trump authorized the launch of a barrage of Tomahawk cruise missiles against a single Syrian airfield in retaliation for Assad's use of sarin gas against civilians.
Assad has repeatedly denied his government has used chemical weapons.
On Wednesday, NATO said the Russian navy is building up its presence in the Mediterranean Sea amid growing tensions over the war in Syria.
"We will not speculate on the intention of the Russian fleet, but it is important that all actors in the region exercise restraint and refrain from worsening an already disastrous humanitarian situation in Syria," NATO's chief spokesman, Oana Lungescu, said Wednesday.
She says several of the Russian ships are equipped with cruise missiles.
Russian defense officials could not be reached for comment.
At least eight ships, including a missile cruiser and two missile-carrying submarines, have joined the Russian flotilla over the past three weeks.
Russian media reports indicate there are around 15 Russian navy vessels in the Mediterranean overall.