COPENHAGEN, Denmark (AP) — Denmark can do more in Europe, French President Emmanuel Macron declared Tuesday as he pushed for a more closely united European Union and a continent that takes more responsibility for its own defense.

On the first day of a two-day visit, Macron pressed the case that the EU shouldn't rely so much on the United States for its own security.

Denmark has a defense opt-out clause in its EU ties, meaning it does not take part in military matters. The Danish government and a majority of lawmakers want the defense waiver to be removed but are hesitant about calling a referendum on it since previous votes on the topic have been defeated twice.

"I believe Denmark is too modest about its European commitment," Macron told a news conference after talks with Danish Prime Minister Lars Loekke Rasmussen. "I think Denmark can do even more in Europe.

"I am not calling for a referendum but for a debate, and it shouldn't just be black or white," Loekke Rasmussen said.

Macron's visit came as France's high-profile environment minister Nicolas Hulot unexpectedly announced his resignation on national radio Tuesday, dealing a blow to the French president's lofty green ambitions.

"Europe is not doing enough. The world is not doing enough," Hulot said. "The planet is becoming an oven, our natural resources are being exhausted, biodiversity is melting like snow in the sun and it's not always dealt with like a priority issue."

Macron initially said he doesn't usually comment on French affairs while abroad, but later called the resignation a personal choice, adding that France would "continue its work" on combatting climate change.

Macron was greeted by Denmark's Queen Margrethe at Copenhagen Airport and laid a wreath at a monument for fallen Danish soldiers before his talks with the Danish prime minister. Later he was joining a debate with students.

Macron also was to visit the site of the Feb. 14, 2015, terror attack in Copenhagen that left two dead and five wounded.

France's departing ambassador to Denmark, François Zimeray, had attended a freedom of speech event targeted by the lone gunman, Omar Abdel Hamid El-Hussein, who sprayed venue with gunfire and killed a bystander. Zimeray was unharmed.

El-Hussein later was also behind a second shooting outside Copenhagen's main synagogue where a guard was killed. The shooter was shot dead hours later.

On Wednesday, Macron will start a two-day visit to Helsinki, where he meets Finnish counterpart Sauli Niinisto and Prime Minister Juha Sipila.