President Trump’s decision to take limited military strikes against a Syrian military base Thursday is a potential game-changer for Syria, but only if the Trump administration follows through with a strategy to increase the pressure on Bashar al-Assad’s regime and its partners, according to the lead negotiator for the Syrian opposition.

Trump said Thursday that he is calling on the international community “to end the slaughter and bloodshed in Syria,” but the administration has not specified whether the strikes will be followed by a significant change in the United States’ Syria policy. If the Trump team treats its reaction to Assad’s use of chemical weapons as a one-off event, Assad, Russia and Iran will claim they stood up to Trump’s aggression and then take retribution on the Syrian opposition and the Syrian people, said Riyad Hijab, a former Syrian prime minister.

“President Trump was able to do in two days what President [Barack] Obama could not do in six years,” Hijab told me Friday morning. “We call on President Trump to go even further and ground the entire Syrian Air Force, which has ruthlessly bombarded civilians with chemical weapons and explosive barrels for years with impunity.”

Short of that, the Syrian opposition is asking the Trump administration to use any new leverage it has to demand a nationwide ceasefire, to stop the killing of civilians by the Assad regime and press for international access to all besieged areas and the jails where Assad is holding thousands of civilians in custody. They also believe now is the time to push for a new political process to move Assad out of power.

Assad saw statements from senior Trump administration officials last week referring to his remaining in power as a “green light” for him to escalate his attacks on civilians, according to Hijab. Now, Trump has backed up his strong words of condemnation of Assad’s April 4 chemical weapons attack with actions, but it’s only the first step.

“If this strike is not followed up by political, military and diplomatic pressure, it will give a chance to Assad to boast they have contained the strike and they have made an achievement,” Hijab said at a pre-scheduled Friday morning event at the Atlantic Council.

The Syrian military command issued a statement Friday pledging to double down on its effort to crush what it calls terrorists, which for Assad includes the Syrian opposition and even civilians.

“That’s why we expect an escalation against the Syrian people,” Hijab said.

The most important determining factor going forward is what the U.S. strategy will be. Hijab, who has been meeting with administration officials, Pentagon officials and lawmakers this week, revealed that the Syrian opposition has submitted two plans to the Trump administration for consideration. One would seek to take advantage of gains in northern Syria, won with the help of the Turkish military, to establish the safe zones that Trump has repeatedly promised.

A separate plan put forth by the Syrian opposition asks for U.S. support to train and equip moderate Sunni Arab fighters in the eastern Syrian provinces of Deir al-Zour and Raqqa, to fight the Islamic State. If the U.S.-led coalition relies on the heavily Kurdish Syrian Democratic Forces to take Raqqa, it will likely defeat the Islamic State but then cause a new war that will result in the rise of a new terrorist group to oppose the Kurds, the opposition contends.

“The good alternative is, use the people from the provinces themselves. The same applies to al-Qaeda in Idlib,” a province in northern Syria, Hijab said.

Even after six years of war, the Syrian opposition and Syrian civilians are still crying out for the United States to lead the international charge to defend their dignity and basic rights, he said. Trump now has a new opportunity to answer their calls.

“The United States is leader of the free, democratic world,” said Hijab, “whether it wants it or not.”