Rumsfeld signaled a harder line against China from the Bush administration, which has criticized Beijing over trade and human rights issues but not directly challenged the Chinese military buildup.
the Bush administration will be tougher with China than previous regimes were
The context states that the Bush administration will take a harder line, so if you are taking a harder line, the logical thought conclusion is that previous regimes were less hard. The system could likely not make this jump in logic and assumed it was possible to tell. 
( z1 tough :ARG1 ( z2 government-organization :ARG0-of ( z3 administrate ) :mod ( z4 person :name ( z5 name :op "Bush" ) ) ) :ARG2 ( z6 country :name ( z7 name :op "China" ) ) :ARG2-of ( z8 have-degree :ARG1 z2 :ARG3 ( z9 more ) :ARG4 ( z10 regime :mod ( z11 previous ) ) ) )