WASHINGTON, Sept. 29 (UPI) -- U.S. Secretary of State John Kerry warned his Russian counterpart the United States will suspend plans to coordinate anti-Islamic State counter-terrorism efforts if Moscow does not stop attacking Aleppo.
Kerry made the comment during a phone call with Russian Foreign Minister Sergey Lavrov on Wednesday.
"Secretary Kerry expressed grave concern over the deteriorating situation in Syria, particularly for continued Russian and Syrian regime attacks on hospitals, the water supply network, and other civilian infrastructure in Aleppo," State Department spokesman John Kirby said in a statement. "The Secretary made clear the United States and its partners hold Russia responsible for this situation, including the use of incendiary and bunker buster bombs in an urban environment, a drastic escalation that puts civilians at great risk."
The conversation between the diplomats followed a short-term cease-fire that began earlier this month in Syria between President Bashar al-Assad's regime and a consolidated group of Syrian rebels. The cease-fire allowed for humanitarian aid to reach many Syrians.
The cease-fire was frequently violated, with attacks attributed to both sides. Last week, Assad declared the cease-fire was over and the regime began attacks on rebel positions, particularly targeting Aleppo, with the aid of Russian airstrikes.
The United States and Russia had planned to carry out joint efforts against Islamic State targets if a cease-fire between Assad and rebels held.
"The Secretary stressed that the burden remains on Russia to stop this assault and allow humanitarian access to Aleppo and other areas in need," Kirby added of Kerry's conversation with Lavrov. "He informed the foreign minister that the United States is making preparations to suspend U.S.-Russia bilateral engagement on Syria ... unless Russia takes immediate steps to end the assault on Aleppo and restore the cessation of hostilities."