Former presidential candidate John McCain on Sunday joined other US lawmakers in calling for American action in Syria in the wake of revelations that President Bashar Assad’s regime ordered chemical weapons to be deployed against civilians in the country.

US officials last week declared that the Syrian government probably used chemical weapons twice in March, newly provocative acts in the two-year-long civil war that has killed more than 70,000 people and displaced hundreds of thousands more. The US assessment followed similar conclusions from Britain, France, Israel and Qatar — key allies, some of whom are eager for a more aggressive response to the Syrian conflict.

President Barack Obama has said Syria’s likely action — or the transfer of Assad’s stockpiles to terrorists — would cross a “red line” that would compel the United States to act.

McCain said the Syrian people, whom he called “angry and bitter,” needed help from the US. The senator said Washington needed to play a larger role in the conflict, warning that children would continue to be killed “unless we assist them.”

McCain cautioned, however, that the US should only take action along with a coalition of other nations. “The worst thing we could do is put boots on the ground,” he said.

“The president has laid down the line, and it can’t be a dotted line. It can’t be anything other than a red line,” said House Intelligence Committee Chairman Mike Rogers, a Republican. “And more than just Syria, Iran is paying attention to this. North Korea is paying attention to this.”

Added Sen. Saxby Chambliss, also a Republican: “For America to sit on the sidelines and do nothing is a huge mistake.”

Obama has insisted that any use of chemical weapons would change his thinking about the US role in Syria, but said he didn’t have enough information to order aggressive action.

“For the Syrian government to utilize chemical weapons on its people crosses a line that will change my calculus and how the United States approaches these issues,” Obama said Friday.

But Rep. Jan Schakowsky, an Illinois Democrat, said Sunday the United States needs to consider those weapons. She said that when Assad leaves power, his opponents could have access to those weapons, or they could fall into the hands of US enemies.

“The day after Assad is the day that these chemical weapons could be at risk … (and) we could be in bigger, even bigger trouble,” she said.

Both sides of the civil war already accuse each other of using chemical weapons.

Republican Sen. Lindsey Graham said the United States could safeguard the weapons without a ground force, echoing McCain’s position. But he cautioned the weapons must be protected for fear that Americans could be targeted. Raising the specter of the lethal bomb at the finish line of the Boston Marathon, Graham said a future attack on US soil could employ weapons that were once part of Assad’s arsenal.

“The next bomb that goes off in America may not have nails and glass,” he said.

Rogers and Schakowsky spoke to ABC’s “This Week”; Chambliss and Graham were interviewed on CBS’s “Face the Nation”; and McCain appeared on NBC’s “Meet the Press.”

Israelis, too, were split Sunday over the prospect of American intervention in Syria.

Environmental Protection Minister Amir Peretz (Hatnua) called for US military intervention in the ongoing civil war.

Peretz said action should have been taken long ago, due to the high civilian death toll. “We expect that whoever defines red lines will also do what is needed, first and foremost the US and, of course, the entire international community,” he said.

Yoav Galant, a prominent former general and candidate for chief of staff, expressed concern that such intervention would hasten the fall of Assad and usher in extremist elements.

“In the short term, the fall of Assad weakens the radical axis. But in the long term, we’ll be facing the extremist organizations that have entered Syria and are establishing themselves therein,” Galant told students on Sunday.

“Things will get worse,” he cautioned.

On Saturday, Prime Minister Benjamin Netanyahu instructed his ministers to stop giving interviews on the situation in Syria, and specifically on the Assad regime’s reported use of chemical weapons.

Netanyahu’s strict orders came in response to deputy foreign minister Ze’ev Elkin’s remarks on Army Radio Friday, in which he was seen to be calling on the international community to take control of, and eliminate, Assad’s chemical weapons arsenal.

The Associated Press contributed to this report