Complex sentence: Jammer is now distinctly uneasy about his own role in the NCP, telling Tyrol that some NCP members might be "in over their heads," but does not reveal his own NCP membership to Tyrol.
Split into simpler sentences: Jammer is now distinctly uneasy about his own role in the NCP, telling Tyrol that some NCP members might be "in over their heads". But does not reveal his own NCP membership to Tyrol.