In the face of nationwide protests over proposed pension reforms, French President Emmanuel Macron insisted he would not allow the protests to stop him from moving ahead with the reforms. Hundreds of thousands of protesters took to the streets of Paris and other French cities Thursday. Protesters’ biggest concern with the reforms was related to plans to raise the retirement age from 62 to 64.

“I want them to withdraw the new retirement age. It’s not acceptable at all. Two additional years, that’s really not possible,” 61-year-old protester Sylvie Le Bas said Thursday. “I work in a kindergarten and the working conditions are worse and worse and two more years, that’s not possible. Physically, no.”

More than 200 rallies were staged around France on Thursday, including a large one in Paris involving all France’s major unions. Most train services around France were canceled, and about 20% of flights out of Paris’ Orly Airport were canceled and airlines warned of delays. The Ministry of National Education said between 34% and 42% of teachers were on strike, depending on schools.

“I trust the organizers of these protests to ensure that legitimate expression of disagreement takes place without causing too much inconvenience to our fellow citizens and of course that it doesn’t get out of hand with violence or vandalism,” Macron said during a news conference at a French-Spanish summit in Barcelona Thursday. Macron went on to justify the pension reforms despite the protests, arguing that in a country with an aging population and growing life expectancy where everyone receives a state pension, reform is the only way to keep the system solvent.

“In countries where people live ever longer, where we have created strong and fair welfare systems which rely on equality between generations, at moments where there are fewer and fewer people who are economically active and more and more who are retired, if you want the pact between generations to be fair, this reform needs to be carried out,” Macron said. “And we will do it in a spirit of respect and dialogue, but with determination and a sense of responsibility.”

The Associated Press contributed to this report.