The Guardian reports that the US government is asking individual EU member states to sign a memorandum of understanding committing to provide additional personal information about air passengers and associated individuals, or lose their rights to visa-free travel to the US.
Under the existing PNR (passenger name record) program, airlines provide 19 items of information on every traveler flying from the EU to the US. Approval of the existing program was quite controversial in the US (the Article 29 Working Party devised an appropriate framework for the transfer). The additional information the US is requesting includes data on all air passengers flying over (and not landing in) the US and data about non-travelers who may be let beyond security to assist in boarding. This information would be combined with the data in the PNR to build out profiles of travelers to assist in detecting and preventing terrorism.
Greece and the Czech Republic have expressed interest in participating, because their citizens are currently subject to visa requirements for travel to the US. But Brussels is pressing for a united bargaining position and urging individual countries not to sign.