U.S. encourages Ukraine to ramp up mobilization

Sullivan made these remarks in an interview with PBS News, where he responded to a question about whether receiving new types of weapons, such as tanks, missiles, or aircraft, earlier would have made a bigger impact.

"We have provided the tanks. We have provided the F-16s. We have provided the HIMARS. We have provided the Patriots. We have provided many of the things that you said earlier we wouldn't provide. And it's not back then. It's, rather, today that Ukraine finds itself in a more challenged position on the battlefield, suggesting that there's not a straight line between those weapons systems and how it does on the battlefield. Where is the straightest line between Ukrainian performance and inputs? It's on mobilization and manpower," Sullivan said.

According to the White House advisor, Ukraine’s mobilization needs to be stepped up.

"Have we seen a marked difference since we have provided tanks to Ukraine in terms of the battlefield? Similarly, on F-16s, have we seen a marked difference? Our view has been that there's not one weapon system that makes a difference in this battle. It's about manpower, and Ukraine needs to do more, in our view, to firm up its lines in terms of the number of forces it has on the front lines. It's about munitions and it's about all of the other things that go to a country's national strength, their morale, their cohesion, their industrial base," Sullivan stressed.

• Journalist Vitaly Portnikov believes that the ongoing Russian-Ukrainian war is driving a global rise in conflicts, setting the stage for a long-term clash between democracies and dictatorships.