The US ambassador to Russia under President Obama slammed President Biden on Sunday for his refusal to provide Ukraine with an advanced missile system that can reach Moscow.

Ex-ambassador Michael McFaul, who is also an MSNBC analyst, called Biden’s approach “a losing strategy” when asked about a tweet he posted that said, “Not arming Ukraine prolongs the war.”

McFaul told MSNBC anchor Katy Tur that there were tense debates within the Biden administration regarding how to proceed with the deadly conflict.

He suggested signing a formal agreement with Ukrainian President Volodymyr Zelensky to send more weapons as long as Ukraine pledges not to use them in Russia.

“Sign a formal agreement saying we will not use these weapons in Russia,” McFaul explained. “I think that’s a better solution than sitting in Washington and trying to modulate and calculate exactly what we want Ukrainians to do on the battlefield.

“And number two, this threat of escalation, we’ve been talking about this for over three months. We keep hearing that we do this, we do that, we do this, we do that — [Russian] President [Vladimir] Putin is going to escalate. And yet what is the evidence about? If the escalation is going to take place inside Ukraine, shouldn’t we trust the Ukrainians to know their security interests better than we do?”

Reports last week indicated the White House was preparing to send long-range systems to Ukraine as Russia persists in its brutal invasion that began over three months ago on Feb. 24. 

On Monday, Biden told reporters “We are not going to send to Ukraine rocket systems that can strike into Russia,” after arriving back at the White House from Delaware — denying Zelensky’s request for Multiple Launch Rocket Systems (MLRS) as well as High Mobility Artillery Rocket Systems (HIMARS).

While other foreign leaders – such as British Prime Minister Boris Johnson – have spoken in support of providing the rocket systems, US officials are wary that the delivery could escalate the conflict further.

A visibly frustrated McFaul said not arming Ukraine is “a losing strategy,” on the network.

“I just think it’s a losing strategy,” said McFaul, who sounded flustered. “There will only be an end to this war in three different scenarios. One, Putin conquers all of Ukraine. Two, Ukraine pushes Russia out of Ukraine. Or three, there’s a stalemate on the battlefield. To me, option two and option three are the ones that we should be supporting and the way you do that is to give the Ukrainians what they need to achieve one of those two outcomes.”

McFaul caught heat back in March after he compared Putin to Adolf Hiter when he claimed even Hitler did not kill ethnic Germans or German speakers while Putin has bombed Russian speakers living in Ukraine during the ongoing war.