United States Senator John McCain on Sunday slammed the Syria truce deal his government forged with Russia, saying it would only empower Moscow's "military aggression".
"Let's be clear about what this agreement does: It permits the assault on Aleppo to continue for another week. It requires opposition groups to stop fighting but it allows Russia to continue bombing terrorists which it insists is everyone, including civilians" said McCain, a leading member of the opposition Republicans and head of the Senate Armed Forces Committee.
"If Russia or the Assad regime violates this agreement, what are the consequences? I don't see any" he told an audience at the Munich Security Conference.
The 17-nation Syria Support Group, co-chaired by Russia and the US, agreed on Friday to seek a "cessation of hostilities" in Syria within a week and dramatically ramp up humanitarian access to besieged towns.
The agreement was described by the countries that took part as a rare diplomatic success in a conflict that has fractured the Middle East and killed at least 470,000 Syrians and injured 1,900,000 others, which made up nearly 11.5 percent of the Syrian population, in the five-year-old war.
The war also left 11 million homeless and sent at least four and a half million fleeing.
However, it had been said that there was no hope for progress without a pause to the Russian bombing, which has decisively turned the balance of power in favour of Assad regime.
Critics have said that the deal is hobbled by the fact it does not include "terrorist" groups such as the DAESH and the Al Qaeda affiliate Al Nusra, leaving room for Russia to continue attacks by claiming it is targeting terrorists.
The agreement followed a major offensive by Syrian government forces, backed by heavy Russian bombing and Iranian troops, on the rebel stronghold of Aleppo.
McCain said it was "no accident" that Russian President Vladimir Putin had chosen this moment for a deal.
"We've seen this movie before in Ukraine" he said. "Russia presses its advantage militarily, creates new facts on the ground, uses the denial and delivery of humanitarian aid as a bargaining chip, negotiates an agreement to lock in the spoils of war and then chooses when to resume fighting."
"This is diplomacy in the service of military aggression and it is working because we are letting it" he said.