WASHINGTON -- Russian President Vladimir Putin and Syrian President Bashar al-Assad are following a formula in which the common denominator is to embarrass the United States, Sen. Bob Corker (R-Tenn.) said Sunday. He added that the "wisest thing" Assad did was use chemical weapons to slaughter 1,200 people, and predicted that Putin will only escalate military aggression in Ukraine if the U.S. doesn't take swift action.

"I think the [Obama] administration is basically saying to Russia, 'Look, don't do anything overt. Don't come across the border with 40,000 troops. Don't embarrass us in that way. But you can continue to undermine the sovereignty of Ukraine by doing the things that you've done,'" Corker said on NBC's "Meet the Press."

Corker, the top Republican on the Senate Foreign Relations Committee, accused President Barack Obama of leading the U.S. with an "air of permissiveness" since the Syrian government used chemical weapons against its own people last August. Corker argued that Putin, like Assad, doesn't believe he will pay any penalty for increasing Russia's military presence in Ukraine following its seizure of Crimea last month.

"It's going to be too late," Corker said. "I hate to say such a crass thing on Easter Sunday morning ... The wisest thing that Assad did really was to kill 1,200 people with chemical weapons. Because, in essence, we said, 'Don't embarrass us anymore that way. You can go ahead and kill another 60,000 people with barrel bombs and by other means, but don't embarrass us.'"

Obama has mostly pursued a cautious approach in Syria, where the three-year civil war has now left more than 150,000 people dead. Last year, the Obama administration said it would move ahead with plans to arm Syrian rebels. A brief proposal in August to engage in targeted military strikes was not pursued in favor of a diplomatic approach, which Secretary of State John Kerry said earlier this month has removed 54 percent of the chemical weapons from the conflict.

Conservatives have nonetheless faulted Obama's foreign policy for being too passive and blamed the president for Putin's actions in Ukraine. Speaking shortly after Corker on Sunday, New York Times columnist David Brooks said Obama has a "manhood problem" in the Middle East.

"Basically since Yalta we've had an assumption that borders are basically going to be borders, and once that comes into question, if in Ukraine or in Crimea or anywhere else, then all over the world all bets are off," Brooks said during a "Meet the Press" roundtable. "And let's face it, Obama, whether deservedly or not, does have a -- I'll say it crudely -- but a manhood problem in the Middle East."

"Is he tough enough to stand up to somebody like Assad or somebody like Putin?" he added. "I think a lot of the rap is unfair, but certainly in the Middle East, there is an assumption that he's not tough enough."

With respect to Ukraine, Obama has signed several executive orders in the last two months consisting of sanctions against Russian officials and key sectors of the Russian economy. One of the orders announced by Obama last month gave the Treasury Department the authority to target individuals and institutions in Russia's financial services, energy, metals and mining, defense and engineering sectors.