President Donald Trump said Saturday morning airstrikes in Syria overnight were "perfectly executed", hours after he announced the US, United Kingdom and France launched precision missile strikes in Syria in response to an alleged chemical weapons attack in Syria last weekend.
Mrs May said it was likely the Assad regime was continuing "with some chemical weapons production".
Mattis says the United States, along with France and the United Kingdom, struck because Syrian President Bashar Assad "did not get the message" when the US launched airstrikes after a chemical attack in 2017.
"When you shoot iron into the air without guidance, it is going to come down somewhere", McKenzie said.
"This is hooliganism in worldwide affairs, and not minor hooliganism, as we are talking about major nuclear powers", the Russian envoy added.
The United States, France and Britain acted morally and responsibly by striking Bashar Assad's chemical weapons program in Syria.
A Pentagon briefing later said the strikes had "set the Syrian chemical weapons programme back for years". He acknowledged, however, that Syria retained "residual" capacity, but gave no details on the scope of what could be left.
In last year's strikes, the Pentagon said missiles took out almost 20 percent of the Syrian air force. After the attack ceased and the early morning skies went dark once more, vehicles with loudspeakers roamed the streets of Damascus blaring nationalist songs.
The strikes also appear to leave Assad firmly in control and with his Russian backing intact.
"One strike does not make for a strategy in an extended campaign to put pressure on Assad and Putin not to do this again", he said.
Weeks later, it became apparent that Iraqis had organized an insurgency, and USA forces remained in the country for years. Damascus state TV was claiming the regime had intercepted some Tomahawk missiles, Fox News reported, although the claim was unverified.
The prime target of the operation was the Barza Research and Development Center in the greater Damascus area, which McKenzie noted was "one of the most heavily defended aerospace areas in the world".
The rhetoric from Syria's backers was harsh.
Scottish first minister Nicola Sturgeon condemned the attacks and accused May of "complying with presidential wishes", while Lib Dem leader Vince Cable warned: "Riding the coat-tails of an erratic USA president is no substitute for a mandate from the House of Commons".
"An act of aggression against a sovereign state that is on the frontline in the fight against terrorism was committed without a mandate from the UN Security Council and in violation of the UN Charter and norms and principles of worldwide law", Putin said in a Kremlin statement.
But there were no signs the Russian military was preparing a retaliatory response that could bring Moscow and Washington into direct confrontation. "This is a regime that murders its people daily". A United States spokeswoman said Friday the allies had "proof".
The use of chemical weapons, such as chlorine, sparks worldwide indignation but is far from being the most lethal weapon in the regime's arsenal. They will collect soil samples and talk to witnesses in attempts to pin down what occurred.
"A perfectly executed strike last night", Mr. Trump said.
"Could not have had a better result". The treaty does, however, prohibit the use of chlorine as a weapon.
"Nothing is certain in these kinds of matters", he said.
Mattis said Friday that the United States had not yet confirmed that the suspected Syrian chemical weapons attack included the use of sarin gas.
Pentagon officials said they met their objectives and struck the heart of the chemical weapons program.
Investigators from the global chemical weapons watchdog swarmed to Douma to begin a gruelling inquiry into the horror gas attack after Russian Federation and Syria shrugged off as non-existent.
In the aftermath of the attack, the western powers set out their justification for military action that was carried out without a mandate from the United Nations and in the face of criticism from Assad's allies Russian Federation and Iran.
Saturday's airstrikes drew support from the European Union, Germany, Israel and other allies. European Council President Donald Tusk tweeted, "The EU will stand with our allies on the side of justice".
■ April 6, 2017: In retaliation for a chemical weapons attack in northern Syria that killed almost 90 people, the U.S. fires 59 Tomahawk missiles at the government-controlled Shayrat air base in central Syria.
McKenzie was asked if a missile attack on a chemical facility posed a risk of dispersing a chemical agent cloud, which could have threatened numerous civilians.
Moscow has denounced the attack on its ally by the U.S., Britain and France.
President Trump's advisers have apparently convinced him to leave US forces in Syria for a little while longer to battle the Islamic State.
Syria's capital has been rocked by loud explosions that lit up the sky with heavy smoke as U.S. President Donald Trump announced airstrikes in retaliation for the country's alleged use of chemical weapons.