WASHINGTON, Feb 23 (Reuters) - The United States will provide Ukraine an additional $2 billion in security assistance, White House national security adviser Jake Sullivan said on Thursday.

"We're going to continue to look at what is necessary, and make sure that we provide what is necessary that Ukraine has what it needs to succeed on the battlefield," Sullivan said at a CNN town hall event, where he announced the additional aid.

He said the Group of Seven (G7) nations will announce on Friday a new round of sanctions that will include countries that are trying to backfill products that are denied to Russia because of Ukraine-related sanctions on Moscow.

"You will see as time goes on the continued erosion of the quality and capacity of the Russian economy, even as Vladimir Putin races to spend money in an effort to prop it up," Sullivan said.

Asked about Ukraine's request for U.S. F-16 fighter jets, Sullivan said from Washington's perspective "F-16s are not a question for the short-term fight. F-16s are a question for the long-term defense of Ukraine."