Taoiseach Brian Cowen has said he believes Barack Obama's presidency will revive the multi-faceted approach to foreign relations favoured by former president Bill Clinton.
Mr Cowen also said that he believed there would be a change of style and substance from the new regime, with a strong commitment to conflict resolution.
His comments, which were made on the eve of the inauguration of Mr Obama as president, were also being seen as making an implicit criticism of some aspects of the foreign policy pursed by the Bush administration.
The Taoiseach was delivering a major speech on foreign policy at Keio University in Tokyo as part of his official visit to Japan.
"The United States remains the world's greatest power but Iraq has exposed the limits of that power and America's need for friends and partners. The spread of liberally democracy, which during the 1990s seemed unstoppable, is faltering in many parts of the world," said Mr Cowen.
In the course of the speech he was critical of Israel, asserting that its response to Hamas' rocket attacks have been disproportionate. "Such action can only further complicate the search for a durable peace," he argued.
"As the tragic and appalling events of the last weeks have reminded us, the Middle East with the still unresolved issue of Palestine at its heart, is an acute source of instability.
"The European Union has a fundamentally important role to play," he said.
Mr Cowen said the world faced very challenging times, with the global financial crisis, the recent events of the Middle East, and the challenge of climate change. No country had been left untouched by these challenges, he said.
Much of Mr Cowen's speech focused on the role of the European Union in international affairs, including its strong relations with Japan. He also said that Ireland's role in shaping developments in the world was greatly improved by working with European partners.
The EU, he continued, was taking a global lead in climate change, with its commitment to a possible target of a 30 per cent reduction in greenhouse gas emissions by 2020, provided the rest of the world signs up to a low-carbon philosophy.
He praised the role played by Japan in this area, describing it as being at the forefront in the development of green technology.
Turning to the Lisbon Treaty, Mr Cowen said that the changed economic circumstances may also have changed the attitude of some of the Irish electorate.
During a question-and-answer session he said: "Ironically, the fact that we have an economic downturn has [highlighted] the role that European Central Bank and the European institutions have played in recent times. The have re-emphasised for Irish people that it is in the European Union that we find that zone of stability that is a prerequisite for our return to future prosperity."
He also rejected the argument from those opposed to integration that the EU was an effort to develop a military capacity for its own sake.
"Of course, that is not the purpose. The EU has no imperial ambitions," he said.
"This portrayal of the development of military capacity as something that is militaristic is a wrong concept. It's about developing military capacity as part of a toolbox that may be needed to provide stabilisation, and the resolution of conflict."
He added: "I feel very strongly that in the Irish debate on these issues it is often presented that because of our preparedness to make that [resource] available to the UN or to the EU it's somehow against our policy of military neutrality. I say quite the contrary."
The Taoiseach pointed out that Ireland and Japan both shared strong commitments to disarmament and to conflict-resolution.
"I believe that the strengths of the relationship between Ireland and Japan, measured in friendship, shared values and deepening economic and political relations, will unite us far more than distance, measured in miles or kilometres, separates us," he said.
Mr Cowen is also meeting the Japanese prime minster Taro Aso today for bilateral talks. He will pay a courtesy call on Emperor Akihito tomorrow before concluding his visit on Saturday.