Russian President Vladimir Putin held on Wednesday a telephone conversation with Saudi Arabia's King Salman to present in detail the proposals contained in a joint U.S.-Russian agreement on ceasefire in Syria, the Kremlin said. "The King of Saudi Arabia welcomed the agreements reached and expressed his readiness to work jointly with Russia to make them work," the Kremlin said. The two sides agreed to continue contacts on this matter, it added. Syrian President Bashar al-Assad also has assured Putin of his government's readiness to respect a ceasefire deal brokered by Moscow and Washington, the Kremlin said on Wednesday. The Kremlin said the two leaders discussed the deal in a phone call and that Assad noted that the proposals laid out in the agreement were an "important step in the direction of a political settlement." Putin, whose air force is flying a bombing campaign to support Assad's troops on the ground, on Monday pledged to do "whatever is necessary" to get Damascus to uphold the deal after sealing the agreement with U.S. President Barack Obama. On Tuesday, U.S. Secretary of State John Kerry warned that it may be difficult to keep Syria whole if it takes much longer to end the fighting after Syria's regime agreed in the same day to the ceasefire deal announced by the United States and Russia. Syria's regime and opposition agreed Tuesday to the ceasefire deal announced a day earlier by the United States and Russia, aimed at halting its nearly five-year civil war.