UK foreign minister: 'Millions will not accept Assad'

British foreign secretary Boris Johnson accused Syrian President Bashar al-Assad of being responsible for the “overwhelming majority" of 400,000 deaths during the five-year “slaughter" in Syria.

“There are millions in that country, who in our view, will not accept rule by him again," Johnson added.

During a speech delivered Friday at the Chatham House think tank in London, Johnson said a new way of moving away from the Syrian president should be found.

Underlining that the future of Syria should mean a united country, Johnson said he could not “see that happening under Assad".

The British foreign secretary also reiterated the U.K.'s commitment to NATO.

“Our resolve to fulfill NATO's obligations will be unbreakable," he said.

Johnson added it could not be justified that 70 percent of the alliance's expenses be met by only one member state -- the U.S. -- and added that every member should allocate 2 percent of their GDP for NATO expenditure.

Johnson emphasized that the U.K. was “prepared to be tough with Russia" but added that this did not mean there was a contradiction between deterrence and dialogue.

“We can't normalize relations with Russia and go back to business as usual," Johnson said, because of situations in Ukraine, Crimea and Syria.

Speaking on Britain's foreign policy, Johnson said the U.K. could not ignore developments across the world.

He said: "We have to acknowledge that in many respects the world is not in good shape...We have the cult of the strong man, we have democracy in retreat, we have an arc of instability across the Middle East, from Iraq to Syria to Libya."

"What is the answer of the U.K.? Is it to cower and put the pillow over our heads? Emphatically not," Johnson added.