President Donald Trump. Reuters US President Donald Trump is reportedly considering military retaliation against Syrian President Bashar Assad after blaming him for a "heinous" chemical attack that killed at least 70 people, including at least a dozen children.

Unnamed sources told CNN that Trump spoke to members of Congress about a potential hit to Assad's forces, but that no decisions had been made yet.

"Yesterday's chemical attack, a chemical attack that was so horrific, in Syria, against innocent people, including women, small children, and even beautiful little babies, their deaths were an affront to humanity," Trump said on Wednesday in the White House's Rose Garden alongside King Abdullah II of Jordan.

However, military strikes against Assad have been considered several times throughout the six-year Syrian civil war. In December, President Barack Obama said the option of military strikes against Assad was not "easily available to us."

Not only are Russian service members in eastern Syria with Assad's forces, but Russia's advanced air defenses would make it a nightmare for the US to strike any of Assad's targets without putting US pilots in grave danger.

Igor Sutyagin of the Royal United Services Institute, who is an expert on US-Russia relations and air defenses, previously told Business Insider that even in the US's stealthiest plane — the F-22 — pilots and planners would have to be "operationally, tactically brilliant" to strike Assad's forces without losing American lives.

Russian S-400 Triumph medium- and long-range surface-to-air missile systems. REUTERS/Sergei Karpukhin

US Navy destroyers could sail to Syria's Mediterranean coast and fire a salvo of cruise missiles at Syrian targets without directly risking the lives of pilots — much like how Obama sent ships to fire on Libya in 2011 — but Russian defense systems could shoot those down, too.

However, Sens. Lindsey Graham and John McCain, members of the Senate Armed Service Committee, have called for a "punitive cost for this horrific attack" to be imposed on Assad via "an international coalition to ground Assad's air force." That likely would mean bombing the runways that Syrian and Russian forces use to launch airstrikes.

Jonathan Schanzer, vice president of research at the Foundation for Defense of Democracies, told Business Insider that while "six years of policy paralysis" under Obama had given Russia and Syria the upper hand in the conflict, Trump still had options.

A covert military strike, short of a loud air campaign, could send a message to Assad that would keep military action out of the public eye.

A second option would be an overt military strike, where US planes would bomb Assad and hope to avoid Russia's advanced anti-aircraft batteries.

This option would directly risk the lives of US soldiers and has become less and less credible as Russia cements the Assad regime's power and its position in Syria.

"The Obama administration ceded Syria to the Russians," Schanzer said. "We did not put up a fight when the Russians stepped in."

In light of the dangers of an air war with top-of-the-line Russian defenses, Schanzer suggested another, less violent option: financial pressure.

"Additional sanctions against Iran and Syria and their enablers could include Hezbollah and any other actor that could be providing support for the Syrian slaughter," Schanzer said.

Syrian President Bashar Assad and Russian President Vladimir Putin. AP

Trump has repeatedly talked tough on Russia, and the US's ambassador to the UN, Nikki Haley, has called on Russia and Iran to stop chemical warfare in Syria.

Though sanctions would not be an eye for an eye, as striking Assad's weapons and runways would be, Schanzer said they would be "easier to implement" with a "significantly lower cost than the deployment of forces or testing the anti-aircraft tech the Russians deployed."