Giuliani says NATO should admit Israel, Japan

"I think we should consider countries such as Australia, Singapore, India, Israel, Japan ... and there are probably a whole group of others that we could put on that list," he said.

The defense alliance has expanded in recent years but its current membership is 26 countries in North America and Europe.

CALL FOR EXPANDED U.S. MILITARY

Facing increasing war-weariness in the United States, Bush last week ordered gradual troop reductions in Iraq but defied calls for a dramatic change of course.

Giuliani, giving the first "Margaret Thatcher Atlantic Bridge" lecture to an audience that included the former British prime minister, called for an expansion of the U.S. military, saying it had cut back too much after the Cold War.

"We need to add at least 10 new combat brigades, that's probably just the beginning," Giuliani said, adding the United States faced not only Islamic terrorism, but also had to consider the possibility of a "large war with a nation state".

Speaking earlier, Giuliani said the United States should spell out clearly to Iran that it would not allow Tehran to acquire nuclear weapons. Giuliani said he had discussed Iran with Brown, his predecessor Tony Blair and Israeli Prime Minister Ehud Olmert in the past few days.

The West suspects Iran is developing atomic weapons but Tehran says its nuclear program is aimed solely at generating electric power.

"The policy of the United States of America should be very, very clear: we will use any option we believe is in our best interest to stop them from being a nuclear power," Giuliani said.