WASHINGTON, September 29. /TASS/. The US is on the brink of calling off the talks with Russia on the efforts to implement a ceasefire agreement in Syria, US Secretary of State John Kerry said on Thursday in a comment on collaboration between the two countries on Syria.

"We are on the verge of suspending the discussion because it is irrational in the context of the kind of bombing taking place to be sitting there trying to take things seriously," Kerry said.

"It is one of those moments where we are going to have to pursue other alternatives," he added.

Russia-US agreement

On September 10, Lavrov and US Secretary of State John Kerry coordinated in Geneva a package of five documents aimed at reinstating ceasefire in Syria and laying down the foundation for the resumption of the political process. The ceasefire came into force on September 12, but Russia’s Defense Ministry has repeatedly stated that the truce has been constantly violated by the opposition.

Attack near Deir ez-Zor

Speculations regarding the likely disruption of the truce in Syria followed a series of incidents that took place over the past few days. The Syrian army’s command on September 17 said that an air raid on Deir ez-Zor left 62 Syrian troops killed and about 100 other people injured. Russian Defense Ministry spokesman Igor Konashenkov said planes of the "anti-Islamic State coalition" attacked Syrian government troops, encircled by IS terrorists in the area of Deir ez-Zor’s airdrome.

"The coalition’s strikes against the positions of government troops in Deir ez-Zor were an outrageous violation of the cessation of hostilities regime. Moreover, the Islamic State (terrorist group outlawed in Russia - TASS) at once launched an attack against government troops," Lavrov said.

Humanitarian convoy attack

On Monday, September 19, a joint humanitarian convoy of the United Nations and the Syrian Red Crescent Society came under attack. Twenty people were reportedly killed. The United Nations said that 18 out of 31 trucks had either been damaged or destroyed. UN Secretary-General Ban Ki-moon has condemned the aid convoy shelling and called for investigation into the incident. Earlier, he described those who stand behind the attack as cowards. The US authorities claim that the convoy came under an air strike. The Russian Defense Ministry said a Predator combat drone of the US-led anti-terrorist coalition was in area of the UN convoy at the moment of the incident. Drones of this type are capable of attacking targets on the ground.