Russia, U.S. push to revive Syrian cease-fire amid new fighting

Renewed fighting in Syria's largest city of Aleppo targeted another hospital Tuesday, as both U.S. Secretary of State John Kerry and Russian Foreign Minister Sergey Lavrov called for reviving a cease-fire that went into effect in late February.

Rocket attacks by rebels on Dubeet Hospital in a government-controlled neighborhood of Aleppo left four dead, according to Associated Press. The Britain-based Syrian Observatory for Human Rights also confirmed the attacks.

Aleppo has been the center of violence over the past 12 days that left more than 250 civilians dead in the contested city, the AP reported. Last week, a government airstrike on a hospital supported by Doctors Without Borders in a rebel-held portion of the city left at least 27 dead.

"There is no justification for this horrific violence that targets civilians or medical facilities or first responders no matter who it is, whether it's a member of the opposition retaliating or the regime in its brutality," Kerry said Tuesday in Washington.

Lavrov, speaking at a news conference in Moscow, said he hoped a new cease-fire covering Aleppo would be announced "in the nearest future, even in the coming hours," the AP reported. He said Russia and the U.S. would work toward creating a rapid response to cease-fire violations in Syria.

The Syrian observatory said more than 3,000 people have been killed in the country since the truce negotiated between the U.S. and Russia was put in place Feb. 27. The cease-fire applied to Syrian President Bashar Assad's military forces and armed opposition groups engaged in a five-year civil war, but excluded terrorist organizations such as the Islamic State and al-Qaeda-linked Nusra Front.

Kerry defended the partial cease-fire for vastly reducing the rate of 200 deaths per day. "Much of the nation is quiet and has remained quiet," Kerry said.

But he said the ultimate success of any cease-fire would include the beginning of a political transition in Syria and allowing humanitarian aid and medical supplies to reach population areas in dire need.

The human rights monitoring group, in its statement, listed hundreds of killings it said were committed by both Syrian government forces and rebel organizations.

The White House had expressed trepidation about the truce when it was first announced.  "We recognize ... this is going to be difficult to implement," White House press secretary Josh Earnest told reporters at that time.