The Outlaws by W.E.B. Griffin and William E. Butterworth IV

The Outlaws: A Presidential Agent Novel - A Presidential Agent Novel.  Charley Castillo and the rest of the Office of Organizational Analysis have been ordered by the President to “disappear from the face of the earth.”  The president has died and his VP, Joshua Clendennen has become president.  Two barrels of Congo-X, the biological material that Charley and crew had removed on their last visit, have showed up in the US. The Russians want to make a deal, exchange of all the Congo-X for two Russians agents who had defected and Charley.