Washington (CNN) State Department spokeswoman Heather Nauert struggled to describe specific steps the State Department and Secretary of State Rex Tillerson are taking to end the violence in Syria at the agency's briefing on Thursday, exclaiming, "I don't know what some of you expect us to do," while arguing that the administration is "fully engaged."

But pressed on whether easing the violence is part of the US mission and what Tillerson is doing to address the bloodshed, the State Department provided few details, pointing instead to statements the agency and White House have released and mentioning conversations with other governments.

"We have a full range of options before us and ahead of us that we can use," Nauert said. "It is not my position, not my role, to be able to say what we will do. Some of those can be defined by other agencies that I can't speak to."

"We are fully engaged," she said.

The Syrian civil war, which began almost seven years ago, is a seemingly intractable regional morass that has only become more dangerous as global powers have been drawn into the conflict and are increasingly at risk of clashing.

Iran, Turkey, Russia, the US, the militant group Hezbollah and Persian Gulf nations are among the entities on the ground, either with their own forces or through proxies. Efforts to de-escalate the war or spare civilians have consistently fizzled.

When pressed for specifics about what the Trump administration was doing or could do, Nauert expressed frustration.

"I don't know what some of you expect us to do," she said. "Our best tool, what we do out of this building is an attempt to do diplomacy. An attempt to shine a spotlight on things that are taking place around the world. That's what I'm doing. ... We will continue to do that. We will continue to take action at the UN Security Council."

Nauert said the US will also "continue to have our people there on the ground, frankly. We have Americans who are there who are assisting Syrians in trying to get back to a normal life. I don't know what more you expect us to do."

The US has "had conversations with the Russian government and reached out to the Russian government to implore them to stop enabling the Syrian regime to do what it's doing to its own people," she said. "Is Russia listening? I'm not sure that they are."

She said the US would "very much like to see" the 30-day UN ceasefire come to pass. "We put out a statement a couple days ago in which we called for that ceasefire," she said. "We will continue to call for that and to put pressure on that."

The UN Security Council will meet at 11 a.m. Friday to vote on the resolution calling for a temporary ceasefire.

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Nauert also made clear that the US holds Moscow accountable for the escalating violence and she called for a return to the internationally backed Geneva peace talks.

"Russia bears a unique responsibility for what is taking place there. Without Russia backing Syria, the devastation and the deaths would certainly not be occurring," Nauert said. She pointed to Russia's provision of weapons and materiel to President Bashar al-Assad's regime. "More than 400 or so civilians have been horrifically killed by the Syrian regime," she said. "And as we all know, they are backed by not only Russia, but also Iran."

Nauert also said the ongoing siege, barrel bombings and starvation highlight the failure of the Astana peace negotiation process, in which Russia, Turkey and Iran -- all parties to the conflict -- are guarantors.

Nauert pointed out that under the Astana plan, Eastern Ghouta is one of several "de-escalation" zones.

"So much for that de-escalation zone," Nauert said. "They have starved people there. They have prevented humanitarian aid from getting in. We have seen innocent civilians killed. We've seen barrel bombs. We've seen this devastation and destruction. That is certainly no de-escalation zone."

The US and its allies want Russia instead to return to the internationally backed Geneva process, the US-led peace effort that has been moribund.

"The United States government and so many other nations stand by the Geneva process as the best way forward to eventually bring peace and eventually bring about a political solution in Syria," Nauert said.