Assad has denied that he is the person responsible for the brutal attack in Khan Sheikhoun, yet most American politicians believe that something needs to be done in Syria.
Russia, an ally of the Assad regime, said the strikes had "completely ruined" the relationship between Moscow and Washington.
Earlier in the day, Johnson announced in a statement published on the United Kingdom government official website that he had canceled his visit to Moscow, scheduled for April 10, due to the recent developments in Syria.
Gabbard told CNN on Friday that she wants to achieve peace in Syria, "Why should we just blindly follow this escalation of a counterproductive regime-change war?"
A few days ahead of the chemical attack, two top USA officials made their clearest pronouncements yet on Syria, saying Washington was not now focused on making Assad leave power and the focus was on defeating Islamic State.
On Thursday night, the United States carried out a missile attack on Ash Sha'irat, located about 40 kilometers (25 miles) from the city of Homs, claiming, with no evidence provided, that the chemical attack on Syria's Idlib was allegedly launched from that airfield.
Earlier, the Foreign Secretary said: "Developments in Syria have changed the situation fundamentally".
"If Russia wants to be absolved of responsibility for future attacks, Vladimir Putin needs to enforce commitments, to dismantle Assad's chemical weapons arsenal for good, and to get fully engaged with the United Nations peacekeeping process".
"We call on Russian Federation to do everything possible to bring about a political settlement in Syria and work with the rest of the global community to ensure that the shocking events of the last week are never repeated".
Sir Michael Fallon accused Moscow of being complicit in war crimes because it is the Syrian regime's main backer.
The general consensus among both parties is that working with the global community in a diplomatic fashion is probably the best strategy in dealing with Assad, but if Trump doesn't go before Congress to explain his future plans and chooses to launch another strike at Syria, could this unleash a serious war? The U.S. used the "deconfliction line" to warn Russian Federation ahead of time that the strike was coming.
British Foreign Secretary Boris Johnson answers a question during a joint press conference with Greek Foreign Minister Nikos Kotzias (not pictured) following their meeting at the Foreign Ministry in Athens, Greece, April 6, 2017.
"The foreign secretary was right to withdraw".
Tillerson conceded that removing Assad from power could "ultimately" require greater pressure, including military action, from the USA or an worldwide coalition, but he said that isn't the preferred choice. "It's right that North Atlantic Treaty Organisation allies speak with one voice". "It is pretty shameful when even Trump judges you to be a buffoon".
He said a solution could only come about if Mr Assad quit as president.
The visit was announced with great fanfare last month as "high level talks" between Mr Johnson and Mr Lavrov - as part of a new policy of "guarded engagement" with Putin's Russian Federation when it is "in the national interest". "Safer in G7 pack?", and adding an audio track by Russian composer Pyotr Tchaikovsky.
That announcement was a significant departure from the Trump administration's stance leading up to the strike.