Arizona senator John McCain on Sunday urged President Barack Obama to “lead” in Syria where a ceasefire agreement was recently breached by forces loyal to the nation’s embattled leader, Bashar al-Assad. The Syrian rebels, according to McCain, are in an uneven fight.

In an appearance on the CBS News morning talk show Face the Nation, McCain argued that the United States should be at the forefront of an international effort to remove Assad from power. “Not lead from behind but lead from in front. They’re waiting for American leadership,” said the Republican senator who was Barack Obama’s rival for the presidency in 2008.

In Seoul last month, President Obama and Turkish prime minister Recep Tayyip Erdoğan agreed to provide “nonlethal” aid to the Syrian opposition. “That doesn’t do very well against tanks and artillery,” said McCain. “We need to get them supplies. We need to get them weapons.”

Other Arab states, including Saudi Arabia, have endorsed the call for weapons supplies but Turkey and the United States are reluctant to intervene so overtly in the Syrian crisis over the objections of China and Russia. The two powers have blocked United Nations Security Council resolutions that deplored the violence in Syria and would have called on Assad to resign.

Referring to the ill-fated “reset” of bilateral relations with Moscow, McCain wondered, “How many times are we going to push that reset button?” before ignoring Russia’s concerns. “It’s time for the United States to lead.”

The septuagenarian legislator was previously a staunch proponent of military action in Libya where an alliance of Arab and Western states enforced a no-fly zone last year when its leader, Muammar al-Gaddafi, like Assad, tried to squelch a popular uprising by force.

Syria is far more divided along ethnic and religious lines than Libya was however and because the geography is vastly different, an expedition could take longer and involve the United States in what is now a bloody civil war.

For these very reasons, America’s top military officer, General Martin Dempsey, cautioned against military support for the rebels in February. “I think it’s premature to take a decision to arm the opposition movement in Syria because I would challenge anyone to clearly identify for me the opposition movement in Syria at this point,” he told CNN.

McCain on Sunday drew the line at directly involving the American military. “No boots on the ground, no unilateral action,” he said. “But for the United States to sit by and watch this wanton massacre is a betrayal of everything that we stand for and believe in.”