A senior official at the US Department of Defense (the Pentagon) reported on Monday that his estimates indicate that up to 80,000 Russians have been killed or wounded in Ukraine since the war began in late February.

US Deputy Secretary of Defense Colin Kahl estimated that the Russian death toll could be "70,000 or 80,000 in less than six months."

He also pointed out that Russian forces have lost "between 3,000 to 4,000" armored vehicles and indicated the possibility that they are suffering from a shortage of precision-guided missiles, including air- and sea-launched cruise missiles, after firing many of them at Ukrainian targets since the attack began on February 24.

He told reporters that these losses are "very striking considering that the Russians have not achieved any of Russian President Vladimir Putin's goals at the start of the war."

He reported that the reduction in Russian use of long-range precision-guided missiles is an indication that their resources have declined to a level that Moscow must maintain as a reserve for other "emergency" situations.

Kahl also acknowledged that the Ukrainian side has suffered heavy casualties, but he did not provide any numbers.

He said: "Casualties occur on both sides. This war is the most intense conventional conflict in Europe since World War II."

However, he pointed out that "the Ukrainians have many advantages, perhaps the most important of which is their determination to fight."