Complex sentence: The Tamil rebel groups were allegedly trained and armed by India, angry with JR about his courting of USA Also the JVP began an intensive attack upon government forces in hope of a socialist revolution which deemed out to be an utter failure.
Split into simpler sentences: The Tamil rebel groups were allegedly trained and armed by India, angry with Jayewardene's pro-American policy. The JVP began an intense attack on government forces in hope of a socialist revolution, but this turned out to be an utter failure.