LONDON — British Foreign Secretary Boris Johnson said Tuesday that “all the available evidence” points to Russian responsibility for the bombing of an aid convoy in Syria.

Johnson told the House of Commons that Russia is “in danger of becoming a pariah nation,” and said he would like to see protests outside the Russian embassy against Moscow’s military actions in Syria.

But he did not mention any new action against Moscow, signaling he does not back calls from several lawmakers for a no-fly zone to be enforced over Syria.

“We cannot do that unless we are prepared to shoot down planes or helicopters that violate that zone, and we need to think very carefully about the consequences,” Johnson said.

Johnson said “our best hope is to persuade the Russians” to “do the right thing” and back a genuine cease-fire.

Hundreds have died in aerial attacks on the opposition-held part of Aleppo since the collapse of a short-lived cease-fire last month. In one incident, on Sept. 19, at least 18 people died in a strike on a U.N.-backed aid convoy. The U.S. blames Russia, but Russia denies responsibility.

Moscow has been a key backer of President Bashar Assad throughout the Syrian conflict.

Britain’s Royal Air Force is part of a U.S.-led coalition attacking Islamic State militants in Syria, but in 2013 lawmakers rejected a government plan to launch RAF strikes against Assad’s forces.

The Russian Embassy in London responded to Johnson’s comments in a tweet, saying Russia’s “record on Syria is thousands of freed villages, thousands of tons of humanitarian aid. What’s Britain’s?”

The recent scenes of civilian suffering in Aleppo prompted Tuesday’s emotional, if inconclusive, emergency debate in Britain’s House of Commons.

Conservative lawmaker Andrew Mitchell, who called the debate, compared Syrian and Russian airstrikes on Aleppo to the notorious bombing of Guernica by fascist Italy and Nazi Germany during the Spanish Civil War.

The U.N. Security Council is deadlocked over how to respond to the Aleppo crisis, with Russia on Saturday vetoing a French-drafted resolution demanding an immediate halt to Russian and Syrian airstrikes and the rest of the council voting down a Russian resolution calling for the evacuation of opposition fighters.