But those concerns seem to have fallen on deaf ears among several defense hawks in Congress.
Sens. John McCainJohn McCainMcCain looking to strike deal with Democrats on Gorsuch nomination McCain responds to North Korean criticism to calling Kim Jong-un 'crazy fat kid' Overnight Finance: Dems seek probe of acting SEC chief | Defense hawks say they won't back short-term funding | Senate seen as start point for Trump infrastructure plan | Dems want more money for IRS MORE (R-Ariz.), Carl LevinCarl LevinSenate about to enter 'nuclear option' death spiral Devin Nunes has jeopardized the oversight role of Congress Ted Cruz wants to destroy the Senate as we know it MORE (D-Mich.), Lindsey GrahamLindsey GrahamOvernight Finance: Dems seek probe of acting SEC chief | Defense hawks say they won't back short-term funding | Senate seen as start point for Trump infrastructure plan | Dems want more money for IRS Overnight Defense: Pentagon considers more troops for Afghanistan | McCain, Graham won't back short-term funding | GOP defends Trump rules of engagement McCain and Graham: We won't back short-term government funding bill MORE (R-S.C.) and Bob MenendezRobert MenendezCorruption trial could roil NJ Senate race Steve Mnuchin, foreclosure king, now runs your US Treasury Senate Dems move to nix Trump's deportation order MORE (D-N.J.) all want Obama to put military pressure on the Syrian regime by creating a no-fly zone and launching air strikes against the country's defenses.
Levin, the chairman of the Senate Armed Services Committee, said it was “essential” that the U.S. “step up the military pressure on the Assad regime.”
Dempsey reiterated the Pentagon's standing concerns on Wednesday.
"It will be difficult because the Syrian air defense system is sophisticated and it's dense," he said.
That said, "if that is a decision that the nation takes that we want to impose a no-fly zone, we'll make it happen," Dempsey added.
American military leaders have reportedly drafted strategic plans for a possible no-fly zone in Syria, located along the country's shared borders with Turkey and Jordan.
U.S. military advisers are working closely with the Jordanian military to address a number of regional security concerns, including Syria.
CIA operatives and U.S. special operations troops have also been training Syrian rebels in Turkey since late last year on using anti-tank and anti-aircraft weaponry, according to recent news reports.
Defense Secretary Chuck HagelChuck HagelSenators tear into Marines on nude photo scandal Lobbying World Who will temper Trump after he takes office? MORE also recently approved a request from Amman to keep a detachment of Air Force F-16s and a Patriot anti-aircraft missile battery in Jordan.
Earlier this year, then-Defense Secretary Leon Panetta ordered a Patriot missile battery to be deployed along Turkey's border with Syria.