US will ensure there is accountability for crimes by Russia: Sullivan

The United States will work with the world to ensure that there is full accountability for the crimes by Russia in Ukraine, US National Security Advisor Jake Sullivan has said.

We had already concluded that Russia committed war crimes in Ukraine and the information from Bucha appears to show further evidence of the same. And as the president said, we will work with the world to ensure there is full accountability for these crimes, he told reporters at a White House news conference on Monday.

The United States (US) is also working intensively with its European allies on further sanctions to raise the pressure and cost on Putin and Russia.

Early in the morning, President Joe Biden told reporters that his Russian counterpart Vladimir Putin is a war criminal.

You may remember I got criticised for calling Putin a war criminal. Well, the truth of the matter -- you saw what happened in Bucha. This warrants him -- he is a war criminal, Biden said on his arrival from his home in Delaware.

But we have to gather the information, we have to continue to provide Ukraine with the weapons they need to continue the fight, and we have to get all the details so this can be an actual -- have a wartime trial. This guy is brutal. And what is happening in Bucha is outrageous, and everyone has seen it, Biden said.

Reiterating that Putin should be held accountable, the President said he is seeking more sanctions against Russia.

We have to consult with our allies and partners on what makes most sense as a mechanism moving forward. Obviously, the ICC is one venue where war crimes have been tried in the past, but there have been other examples in other conflicts of other mechanisms being set up. So there is work to be done to work out the specifics of that, Sullivan later told reporters in response to a question.

Between now and then, every day what we are focused on is continuing to apply pressure on the Russian economy and provide weapons to the Ukrainian people to be able to defend themselves, he added.

Sullivan told reporters that Russians have now realised that the West will not break.

At this juncture, we believe that Russia is revising its war aims. Russia is repositioning its forces to concentrate its offensive operations in eastern and parts of southern Ukraine rather than target most of the territory, he said.

All indications are that Russia will seek to surround and overwhelm Ukrainian forces in eastern Ukraine.

We anticipate that Russian commanders are now executing their redeployment from northern Ukraine to the region around the Donbas in eastern Ukraine, he added.

Russian forces are already well on their way of retreating from Kyiv to Belarus as Russia likely prepares to deploy dozens of additional battalion tactical groups, constituting tens of thousands of soldiers, to the front line in Ukraine's east, he said.

We assess Russia will focus on defeating Ukrainian forces in the broader Luhansk and Donetsk provinces, which encompasses significantly more territory than Russian proxies already controlled before the new invasion began in late February, Sullivan said.

The Ukrainians, he said, are effectively defending themselves with US produced air defense systems and anti-tank systems, such as Stingers and Javelins, as well as radar systems that give the Ukrainians early warning and target data, and multiple other forms of arms and munitions.

The administration is working around the clock to fulfill Ukraine's main security assistance requests, delivering weapons from US stocks where they are available, and facilitating the delivery of weapons by allies where allied systems better suit Ukraine's needs, the official added.