WASHINGTON – The U.S. State Department announced Monday it had suspended bilateral talks with Russia over the failed cease-fire in Syria’s five-year-old civil war, saying Moscow had “failed to live up to its own commitments.”

The cessation of talks was announced amid worsening diplomatic relations between Washington and Moscow, and just after aid groups said their hospitals have been apparently directly targeted by a Russian-led bombing campaign. Activists have blamed the Russian government for 9,000 deaths​ in the last year.

In a statement, spokesman John Kirby said “Russia and the Syrian regime have chosen to pursue a military course, inconsistent with the Cessation of Hostilities, as demonstrated by their intensified attacks against civilian areas, targeting of critical infrastructure such as hospitals, and preventing humanitarian aid from reaching civilians in need, including through the September 19 attack on a humanitarian aid convoy​.”

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The U.S. and Russia had negotiated a short-lived and largely unsuccessful cease-fire​ that included a military coordination deal. As part of the suspension, the U.S. is withdrawing personnel that it had dispatched to take part in the creation of a joint U.S.-Russia center. That center was to have coordinated military cooperation and intelligence if the cease-fire had taken hold. The suspension will not affect communications between the two countries aimed at de-conflicting counter-terrorism operations in Syria.

Much of the tension between the two sides has centered around the government offensive against the rebel-held Aleppo​, Syria’s largest city, which has seen at least 400 civilians killed since the cease-fire collapsed, according to activists. The violent bombardment of civilian areas the city, sometimes allegedly by Russian planes, has turned the city into what one U.N. observer called a “slaughterhouse” of children​.

Syria activists said Monday that warplanes have once again targeted one of the largest trauma and emergency hospitals in the besieged, rebel-held part of Aleppo, this time rendering it “not salvageable.”

Adham Sahloul, of the U.S-based Syrian American Medical Society, which supports the hospital, said a bunker-busting bomb punched a 10-meter-deep crater where it landed Monday at the hospital’s front entrance.

Sahloul says at least three maintenance staff were killed, including one found 330 feet away, apparently thrown by the impact of the explosion.

The hospital has been targeted twice in the last week.

The Britain-based Syrian Observatory for Human Rights confirmed the bombing, but put the death toll at six.

Sahloul says most of the hospital’s facilities were set up underground to protect it. He says there are fears the rest of the building could collapse. Rescue workers are still searching for people under the rubble.

Qatar also said Monday it has closed a health center it was running in Aleppo after the facility was struck by bombs over the weekend.

The Qatar Red Crescent said four bombs were dropped from a helicopter on the hospital in the rebel-held neighborhood of Sakhour on Saturday.

QRS said on Monday that the attack killed two patients, wounded eight and destroyed half the center. Initially, the Qataris had reopened the facility, which was originally built by the Syrian Arab Red Crescent, in April.

Dr. Hashem Darwish, the head of the health program at the QRCS’s mission in Turkey, called the attack a war crime.

The QRC statement came two days after doctors and activists said bombing had put the hospital known as M10 out of service.

In addition to Aleppo hospitals apparently being targeted, a relief group and Syrian opposition monitors said airstrikes have damaged and put of service one of the country’s most secure hospitals, which had been dug into a mountain.

The International Union of Medical Care and Relief Organizations, or UOSSM, says the Dr. Hasan Al-Araj - also known as “Cave Hospital” and located in the central province of Hama - was struck twice on Sunday.

The Britain-based Syrian Observatory for Human Rights said on Monday that Russian warplanes carried out the attacks that hit the hospital near the central village of Kfar Zeita, adding that it’s one of the largest hospitals in rebel-held areas of the country.

UOSSM said there were minor injuries from the attack.