A spokesperson for EU foreign policy chief Federica Mogherini said that the EU has already taken "decisive steps" to build up European security and defense in recent years, including the development of a joint defense fund and a new planning cell for EU military missions around the world.
"I don't necessarily share the same opinions as Nicolas Hulot, but I can understand that he feels betrayed today, like a lot of French people, by the strong promises that were made and the sense that in the end they have not been kept", said Laurent Wauquiez, head of the rightwing Republicans party.
Militant environmentalist Nicolas Hulot resigned from his position as France's minister of ecological and solidarity-based transition this morning during a live breakfast show on national radio.
French President Emmanuel Macron is calling for increased defense in an effort to enhance European security.
Hulot is a former television presenter and green activist who enjoys a popular following with the younger generation of French voters, many of whom grew up watching his nature program on television in the 1990s.
Hulot said he had not informed either Macron or Prime Minister Edouard Philippe of his decision.
Government spokesman Benjamin Griveaux expressed bemusement at Hulot's departure, which the government "regretted". "He didn't win all his battles but that's the way it goes for ministers". "It's up to us to meet our responsibilities and guarantee our security, and therefore European sovereignty".
Emmanuel Macron's climate commitment to "make this planet great again" has come under attack after his environment minister dramatically quit, saying the French president was not doing enough on climate and other environmental goals.
German Chancellor Angela Merkel has said that she supports the idea of a European security council as well as the project of European intervention troops, a notion also favoured by France.
He also explained that he felt alone against the agriculture minister, Stephane Travert, who is considered to be a defender of intensive farming and glyphosate, a weedkiller.
Hulot had told the newspaper Libération this month, in off-the-record comments made public by the paper after his resignation, "My problem is very simple: Either I leave and it will be much worse, or I stay and there will be no revolution".
Hulot's resignation is an "environmental emergency", says Patrick Monfort, who studies the impact of climate change on microbial ecology at the University of Montpellier in France.
"I think that in 15 months, this government has done more than any other on the subject in the same period".
Hulot, a TV celebrity and veteran environmental activist, joined Macron's government in May a year ago and has since struggled to fit in with other members of the cabinet and its general policies.