Iranian general Qassem Soleimani “posed a threat to all our interests” and was responsible for a pattern of disruptive, destabilizing behavior in the region, British Prime Minister Boris Johnson said Sunday.

Johnson, who had until now remained silent over the assassination early Friday of the commander in a U.S. drone strike in Baghdad, said Soleimani played a “leading role” in actions that have led to the “deaths of thousands of innocent civilians and western personnel. We will not lament his death."

“It is clear, however, that all calls for retaliation or reprisals will simply lead to more violence in the region," he said, adding the U.K. is in close contact with all sides to encourage deescalation.

"I will be speaking to other leaders and our Iraqi friends to support peace and stability," Johnson said.

He added that the U.K. has taken steps to increase security in the region to protect British personnel and interests.

Foreign Secretary Dominic Raab earlier Sunday urged Iran to take a diplomatic route to deescalate tensions following the killing of Soleimani.

Speaking on the BBC, Raab said U.S. President Donald Trump and his French counterpart Emmanuel Macron "left the door open to a diplomatic route through this, to a better place for Iran," but that Tehran decided not to take it.

He stressed the need to deescalate tensions and to attempt to restore stability as well as contain Iran's "nefarious actions".

"Iran has for a long period been engaged in menacing, destabilizing activities," he added.

UK on same page with US

Raab spoke separately to Sky News, saying the U.K. was "on the same page" with the U.S. in relation to Friday's killing of Soleimani.

"Let’s be very clear: he was a regional menace, and we understand the position that the Americans found themselves in, and they have a right to exercise self-defense," he said.

"They have explained the basis on which that was done, and we are sympathetic to the situation they found themselves in.”

Meanwhile, the Foreign and Commonwealth Office (FCO) updated their travel advice on Iraq for British citizens.

"The first job of any government is to keep British people safe," Raab said in a statement.

He added that given "heightened tensions" in the region, the FCO advised U.K. nationals not to travel to Iraq with the exception of the Kurdish regional government and to consider carefully whether it is essential to travel to Iran.

"We will keep this under review," he added.

Warships sent to Persian Gulf

Two British warships have been sent to the Persian Gulf to protect ships and citizens, Defense Secretary Ben Wallace announced Saturday.

"Under international law, the United States is entitled to defend itself against those posing an imminent threat to their citizens," Wallace added.

The U.K. Royal Navy escorted British-flagged vessels through the Strait of Hormuz in July last year following Iran's seizure of a British-flagged ship.

The seizure came in retaliation for the seizure of an Iranian-flagged tanker near Gibraltar, a British territory.

Tensions between the U.S. and Iran have mounted following the assassination of Soleimani, the commander of the Islamic Revolutionary Guards' Quds Force, when a U.S. drone struck his convoy outside Baghdad's airport early Friday. Soleimani was killed along with Abu Mahdi al-Muhandis, the senior commander of Iraq’s Hashd al-Shaabi force, and eight others.

On Saturday, Trump threatened to strike Iranian targets in response to any retaliation on U.S. nationals or assets.