Shiite fighters from the Hashed al-Shaabi enter the village of Abu Shuwayhah, south of jihadist-held Mosul, onTuesday, during the ongoing operation to retake the last major Islamic State stronghold in Iraq. (Ahmad Al-Rubaye/AFP/Getty Images)

Civilians have no escape route from the Iraqi city of Mosul and are under threat of “possible mass casualties” from daily U.S. and coalition airstrikes aiding the ongoing Iraqi government offensive to reclaim the city from the Islamic State, Russia’s Defense Ministry said Tuesday.

Maj. Gen. Igor Konashenkov, a ministry spokesman, contrasted the situation in Mosul with that of Aleppo, the Syrian city surrounded by Russian-aided government troops where an estimated 275,000 civilians are stuck inside, along with thousands of antigovernment rebels who Russia says have blocked their exit.

On Monday, State Department spokesman John Kirby called Moscow’s attempts to compare the situations in Aleppo and Mosul “ludicrous” and “absolutely insulting.” Both the United States and the United Nations said Tuesday that they had no reports of civilian casualties attributed to coalition or Iraqi forces during the Mosul offensive that started two weeks ago, and Kirby pointed to extensive preparations made for the safety of civilians who escape or remain in the city.

Russia has been stung by widespread international charges that its air attacks in Syria, including air bombardment of rebel-held eastern Aleppo, have intentionally caused hundreds of civilian deaths.

The complex military battle to retake Mosul from the Islamic State has begun. Here is what you need to know about the ancient Iraqi city. (Ishaan Tharoor, Kareem Fahim, Jason Aldag/The Washington Post)

The exchange was part of a series of public exchanges that have characterized dialogue between Moscow and Washington in the absence of progress to end the Aleppo siege.

The tendentious remarks came as Syrian President Bashar al-Assad told Western journalists invited to interview him in Damascus that he intended to stay in office at least until his current term ends in 2021. “If you’re the captain of the ship, when you have a storm, you don’t jump into the water,” he reportedly said. “You lead it to shore.”

Far from trying to destroy the Islamic State in both Syria and Iraq, Assad told the group, including journalists from the New York Times and the New Yorker, that the United States is supporting both that group and al-Qaeda allies in Syria.

“The whole argument that the United States wants to fight ISIS is not correct,” Assad said, according to the New Yorker. “This is an illusion and information.” The actual U.S. goal, he said, is to topple his government.

“The government doesn’t fit with the criteria of the West or the United States. . . . They want to change Syria, and we are not going to allow this.” ISIS is another term for the Islamic State.

While U.S. and Iraqi officials reported progress in the Mosul campaign, and the imminent start of a similar offensive against the Islamic State in the Syrian city of Raqqa, the separate Syrian civil war has, if anything, become even more complicated.

Russian Defense Ministry spokesman Maj. Gen. Igor Konashenkov speaks at a briefing in the Russian Defense Ministry's headquarters in Moscow, Oct. 20, 2016. (Pavel Golovkin/AP)

On Sunday, Staffan de Mistura, the United Nations envoy for Syria, said he was “appalled and shocked” by “indiscriminate” opposition rocket attacks across the city’s front lines that had reportedly killed scores of civilians.

“Those who argue that this is meant to relieve the siege of eastern Aleppo should be reminded that nothing justifies the use of disproportionate and indiscriminate weapons, including heavy ones, on civilian areas and it could amount to war crimes,” de Mistura said.

“The civilians on both sides of Aleppo have suffered enough due to futile but lethal attempts of subduing the city,” he said.

Russia appeared to argue that its suspension of air attacks in the city for the past two weeks had put it on the moral high ground, leading to its comparison with U.S. air activities in and around Mosul.

“In Mosul, we hear about an imminent storm of city districts inhabited by civilians, which is fraught with obscure but extremely alarming consequences because of possible mass casualties,” Konashenkov said. By contrast, he said, “Russia and Syrian authorities have set up six humanitarian corridors with hot meal and medical aid stations in Aleppo, through which civilians are willing to exit the city but cannot do so, as the approaches to them have been mined, and militants keep shelling them.”

Russian Defense Minister Sergei Shoigu, in a teleconference with Russian army chiefs reported by Tass, charged that insurgents have been executing civilians every day who try to reach “humanitarian corridors” offered to exit the city.

The so-called “surround and starve” tactic of the government, which has refused to allow the United Nations and other humanitarian groups to bring food and medical aid into nearly all besieged towns — in some cases for years — has succeeded in emptying several areas of civilians, a potential violation of international law.

Residents reached inside eastern Aleppo have told reporters that they refuse to leave the city.

Meanwhile, as U.S. officials continued negotiations with Turkey over its participation in the campaign to eject the Islamic State from Raqqa, the chief of Turkey’s military met Tuesday in Moscow with his Russian counterpart.