At a news conference, Biden also said that talking with some members of the Taliban militia is a strategy "worth exploring."
"I do think it's worth engaging and determining whether or not there are those who are willing to participate in a secure and stable Afghan state," he said.
Biden said that he agreed with U.S. envoy Richard Holbrooke's estimate that 5 percent of Taliban members are irredeemable, but that 25 percent might be open to persuasion and that 70 percent were paid fighters simply following the Taliban for economic rewards.
During his visit to NATO and European Union headquarters in Brussels, Biden sought to assure European leaders that their voices were being heard on issues related to Afghanistan, and to gain further support from European countries.
"None of us can escape the responsibility to meet these threats," Biden said at a news conference, according to the Washington Post.
However, he stopped short of asking for increased troop deployments from European countries. President Obama recently ordered 17,000 more U.S. troops to join the 38,000 already in Afghanistan, as part of a broader review of war policy in Iraq and Afghanistan.
But several European governments have already said they are not willing to send more troops, though they are open to contributing in other ways.
"EU countries in principle do not think they will increase the number of their troops which they want to deploy in Afghanistan," EU foreign policy chief Javier Solana told a Spanish radio station, according to the Agence France-Presse. "The situation in Afghanistan is not going to be resolved only militarily. There are many things that can be done in Afghanistan that are not exclusively increasing the number of troops."
European officials have said that they could contribute to police training, civilian reconstruction and election assistance, according to the AFP.