U.S. officials sought to shore up support Sunday for a tougher stand against Iran’s nuclear program by saying Tehran had left the world little choice and expressing renewed confidence that holdout China would come around to harsher U.N. penalties.

Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, called for more time for diplomatic pressure to work and said from Israel, which has hinted that it might attack if negotiations to contain Iran’s nuclear ambitions failed, that such action could have “unintended consequences” throughout the Middle East. Israel views Iran’s nuclear program as a threat to its very existence.

Secretary of State Hillary Rodham Clinton, on a quick visit to Persian Gulf allies Qatar and Saudi Arabia, said Iran has a right to nuclear power, but only if shown unequivocally it is to be used just for peaceful purposes.