On the USA airstrike on an Assad regime air base in retaliation for the chemical attack, Lavrov said, "We reiterated our common position that it was an act of aggression, a flagrant violation of the principles of worldwide law and the UN Charter".
Writing in the Sunday Telegraph, Johnson said the defence was "absurd and mendacious" and described the premier as an "arch-terrorist" and "literally and metaphorically toxic". "At the right time everyone will come to their senses & there will be lasting peace!"
However, Johnson has faced criticism for not persuading G7 countries to agree to sanctions against Russian Federation for its ties with Assad.
Syria has denied responsibility and Russian Federation has claimed that a rebel weapons cache was hit, an impossibility according to chemical weapons expert Hamish de Bretton-Gordon, writing for MEE.
U.S. president Donald Trump launched airstrikes against Syria after a gas attack in the country that killed 70 people.
On Wednesday, UK Ambassador to the United Nations Matthew Rycroft said at the UN Security Council that UK specialists had detected sarin or a sarin-like substance in samples taken from the site of the supposed chemical attack in Syria.
The US hit the Syrian airbase from which it said the assault was launched with cruise missiles, days after the attack. With the help of Russians and Iranians, and by dint of unrelenting savagery, he has not only recaptured Aleppo.
Before the April 4 chemical attack, the West was "on the verge of a grim consensus", which had now changed, said Johnson.
The plan breaks down into three basic phases: defeating the Islamic State group, restoring stability region-by-region and securing a political transition in which Assad ultimately leaves power.