WASHINGTON 

Vice President Joe Biden on Wednesday left open the possibility of lethal defensive aid for Ukraine.

It's "worth having" the debate about whether to assist Ukraine with lethal defensive aid, Biden said. “Helping Ukraine against Russian aggression is critical to checking further aggression down the road.”

Biden’s remarks were made during an address on the Russia-Ukraine conflict and its implications for European security at the Washington-based Brookings Institution.

"Let's not lose sight of the fact that Ukraine also needs basic military equipment and training, which we are also providing on the ground," Biden said.

The White House has resisted arming Ukraine against Russian separatists, but Republicans have pushed for the supply of lethal weapons.

Biden said the U.S. has already furnished Ukraine with nearly $500 million in economic aid since the beginning of the crisis and will potentially add $3 billion in loan guarantees by the end of the year if Kiev continues to implement democratic reform measures.

He also said U.S. sanctions against Russia "will remain in place until the Minsk agreement is fully implemented”, which requires an immediate and full cease-fire in Ukraine, and the withdrawal of all heavy weapons by both sides.

The sanctions are not aimed at forcing "regime change" but are intended to force Russian President Vladimir Putin to act more rationally, he said.