Kerry blamed Russia's "ham-handed" efforts of the past few days to incite chaos in Eastern Ukraine on a growing sense of unease over whether sanctions would be effective in halting President Vladimir Putin's ambitions.
"This is not the bi-polar, straightforward choice of the Cold War," Kerry cautioned. "We're living in an incredibly challenging time where some of the things that East-West order I took for granted most of my life are suddenly finding a world in which American engagement is more critical and in many ways, it's more complicated."
The secretary, who served on the foreign relations committee for nearly three decades, did not shy away from accusing Russia of sending "provocateurs" into Ukraine in an effort to create an excuse to enter the region.
"This could potentially be a contrived pretext for military intervention just as we saw in Crimea,” Kerry said. “No one should be fooled, and believe me: No one is fooled.”
Still, Kerry was firm in his insistence that sanctions -- both those that Congress has already passed and potential expanded sector sanctions, should Russia continue to act with impunity -- would be imposed to their desired effect.
"We are sending a signal today of the clarity of our intention to use whatever sanction is necessary if they continue," he said.
"President Obama has brought sanctions, and it’s having an impact," Kerry said. "And the fact is that it will have a far more serious impact if they cross over or continue what's happening in Eastern Ukraine."
But Sen. John McCain, who has traveled to Ukraine in recent months and has been outspoken in urging the U.S. to send military aid to Ukraine, called the administration's diplomatic gestures "the logic of appeasement."
"What you're doing is talking very big but carrying a very small stick," McCain charged. "A twig, actually."
"Before you ask the American people to go to war, we have an obligation to exhaust the remedies that are available to us in order to legitimize whatever subsequent action we might have to take," Kerry countered.
Besides, Kerry said, military intervention would not come soon enough, once Ukrainians were trained to make an impact on Putin's calculations.
"Which is the greater deterrent?" he said. "We happen to believe right now that if the deterrence you're looking for is going to have an impact, the greatest deterrence will come from Putin's recognition of his own vulnerabilities in his economy and his recognition that if we bring sector sanctions, Russia is going to really hurt."
Committee Chairman Robert Menendez expressed fears that Russia has been deliberately acting to undermine U.S. efforts to end the conflict in Syria and to negotiate with Iran to prevent its nuclear arms development.
"Is it the administration’s intention to sanction those actions?" Menendez asked.
"We meet with Russia to broker a deal with Syria in September, we have a worsening humanitarian disaster and the delay of chemical weapons," Menendez said. "We meet with Russia over Iran, and there's an oil-for-goods deal with Russia and Iran that sources say could be worth $20 billion. Russia annexes Crimea and destabilizes the Ukraine."
"I’m beginning to wonder what it is that, at what point in this relationship with Russia, particularly vis-à-vis Iran but even beyond, is it going to be clear that there consequences?" he asked.
Kerry replied he is hopeful that, in those issues, Russia would still prove to be a reasonable partner.
"There are plusses and yes, there are minuses, obviously," Kerry said. "We don’t have the luxury as a country. You’ve got to deal, at this point, at one timer or another."
"Reagan dealt with Gorbachev, you know?" he said. "Nixon dealt with Mao. It's a reality of the world that we try to move forward."