The newly confirmed US Secretary of State, Rex Tillerson, will approach foreign policy very differently to President Donald Trump. While Trump's guiding principle is "America First", Tillerson espouses an assertive vision of US global leadership.

Unlike Trump, Tillerson believes NATO is indispensable, champions the benefits of US alliances, wants the United States to push back against Russian expansionism in Crimea, and does not oppose the TPP. Tillerson and Trump agree on just one major foreign policy issue: they both favour a tougher stance towards China.

Notwithstanding their considerable differences, Tillerson enters office with "tremendous respect" from the president. Trump has described the former ExxonMobil CEO as a "world-class player", in a different "league" to other candidates for secretary of state.

Tillerson faces a steep learning curve as he transitions from oil man to diplomat. He has demonstrated many of the skills required by a secretary of state – mastering complex political briefs and making strategic decisions leading a $US370 billion ($488 billion) company with operations in more than 50 countries. He follows in the footsteps of senior corporate executives who have run State or Defence, including George Schultz, Casper Weinberger, Bob McNamara and Dick Cheney. However, each of those had significant experience in government or the military.

Though Tillerson might find this transition difficult, his reputation as a business leader and performance under intense questioning from the Senate Foreign Relations Committee indicates that he has the temperament and intellect to be a successful secretary of state.

Power within the cabinet

The secretary of state is often regarded as the second most important position in the US government, but the effectiveness of different secretaries has depended on their relationship with the president and relative power within the cabinet.Tillerson will probably find an ally in Secretary of Defence James Mattis, who shares many of his broad foreign policy views. A formidable operator, Tillerson will need more than one ally if he is to avoid costly inter-agency turf wars, reconcile policy differences with the president, maintain a strong relationship with the White House, and shape the Trump administration's foreign policy.

A clear gap exists between Trump's America First platform and Tillerson's recitation of many of the core tenets of Republican foreign policy orthodoxy. At a minimum, Tillerson's preparedness to disagree with the president during his confirmation hearing indicates that he will be unafraid to have substantive private policy debates with President Trump.

In his prepared opening statement to the Senate Committee on Foreign Relations on January 11, Tillerson pledged that the Trump administration would maintain America's "indispensable" role in the world, providing "moral leadership" to promote stability, increase prosperity and advance liberty. These sorts of phrases are not remarkable on their own, but they are significant in the context of President Trump's nationalist impulses and rejection of the US foreign policy establishment.

Under questioning from senators, Tillerson distanced himself from Trump's pronouncements on a range of important Asia issues. Asked if he agreed with Trump that it wouldn't be a bad thing if countries like Japan and South Korea had nuclear weapons, Tillerson replied "I do not agree". He said the United States must do more to "show back-up in the region with our traditional allies in south-east Asia" that were threatened by Chinese activities in the South China Sea. Tillerson emphatically said "I do not oppose TPP", but questioned whether the deal served "all of America's interests".

Australian officials will be reassured by Tillerson's approach to Asia, because it accords with Australia's national interests, and will hope that President Trump can be persuaded to move in Tillerson's direction on Asia policy.

Anti-Chinese administration

The same cannot be said for China policy. President Trump is assembling the most anti-Chinese administration in recent memory. Although Tillerson acknowledged China's value as a partner in his opening statement to the Senate Foreign Relations Committee, he talked tough on China, equating China's island building in the South China Sea with Russia's annexation of Crimea. Most pointedly, he called for the United States to blockade China's access to man-made islands in the area. These comments should not necessarily be taken literally – Tillerson may have misspoken – but there is every indication that the United States will adopt a tougher stance towards China.

Against this backdrop, Australia will likely find it increasingly difficult to maintain the established Australian foreign policy mantra of an "ally in Washington" and a "friend in Beijing". Domestic debate on the alliance may sharpen.

Australia is nonetheless well placed to try to shape Tillerson's thinking on China. Tillerson is attuned to Australia, having visited for business and overseen major ExxonMobil projects in Australia and Papua New Guinea. Though Tillerson had deep engagement with political leaders across the world during his career as an oil executive, he is relatively unknown in China. He will therefore need to build relationships quickly with his counterparts in Beijing, and will likely be open to Australian counsel on his emerging approach to China.

Rex Tillerson has the foreign policy views of a traditional Republican; he is certainly not "Trump lite". His success or otherwise as secretary of state will shape the extent to which the Trump administration hews to an undiluted America First foreign policy.