Washington: Amidst a sea of contradiction on Donald Trump's foreign policy, Rex Tillerson has raced ahead of the administration pack.

The secretary of state, reclaiming America's role as the world's policemen, declared Washington would come to the defence of innocent civilians "anywhere in the world."

After a year of being pummeled with Trump's inward looking, isolationist "America First" doctrine, Americans awoke on Monday to something very different .

"We rededicate ourselves to holding to account any and all who commit crimes against the innocents anywhere in the world," Tillerson told reporters in Italy.

He spoke at the site of a 1944 Nazi massacre in Italy.

On his way to Moscow for talks with his Russian counterpart, Tillerson's commitment was a powerful but discordant note in the Trump administration's effort to convey any sense of a unified, all-on-the-same-page foreign policy.

It comes at a time when Moscow is warning that in punishing Syrian dictator Bashar al-Assad for a chemical weapon strike in which more than 80 people died, Trump has put the US "on the verge of a military clash with Russia."

That 59-missile barrage has unleashed intense diplomacy around the Syrian conflict, but it coincides too with an historic low in US-Russia relations that is freighted with greater tension than might be expected.

This is because Trump, as a candidate, sold himself as the deal-maker who would get along with Moscow – a prospect that gained credence with Moscow's enthusiasm for Trump's candidacy which included its meddling to give Trump a leg-up over his rival Hillary Clinton.

Tillerson's Italy comments seemed to contradict his own world view stated as recently as Sunday – which seemed to contradict US United Nations Ambassador Nikki Haley's position on Syria on the same day. Both were contradicting their own positions on Syria which they had expressed just days before the chemical attack on Khan Sheikhun, in Syria's Idlib province.

On Sunday, getting rid of Assad, who is accused of "crimes against the innocents" on an industrial scale, was a lesser issue for Tillerson. He said then the top US priority in Syria was defeating ISIS and "the Syrian people in fact will determine Bashar al-Assad's fate and his legitimacy".

But for Haley, "getting Assad out" was one of "multiple priorities" held by the administration.

"We've got to go and make sure that we actually see a leader that will protect his people, and clearly, Assad is not that person," she told CNN.

When National Security Adviser H.R. McMaster was asked to thread the same needle, he told Fox News Sunday that both Haley and Tillerson are right.

That's the context in which Tillerson is said to be ready to confront Russian Foreign Minister Sergey Lavrov with a blunt choice - either Moscow cuts its ties with Assad and is rewarded by better relations with the West; or it stays with Syria as it descends into a Libya-like disaster zone. In that scenario, Russia will continue to get a bad rap from the West.

As a lever, Tillerson is expected to use American intelligence claims of a Russian presence at the Sharyat airbase, to accuse Moscow of complicity in the attack.

"I hope Russia is thinking carefully about its continued alliance with Bashar al-Assad, because every time one of these horrific attacks occurs, it draws Russia closer into some level of responsibility," Tillerson told ABC's This Week.

National security adviser HR McMaster was even more direct, telling Fox News: "I think what we should do is ask Russia, how could it be, if you have advisers at that airfield, that you didn't know that the Syrian air force was preparing and executing a mass murder attack with chemical weapons?"

Meanwhile, as the administration talks up its threats of further action, the Syrian regime's allies are drawing "red lines" which they say if crossed will provoke retaliatory attacks.

Rather than coming from their capitals, a joint command centre that comprises Russian, Iranian and allied militia forces, issued a statement through the media outlet Ilam al Harbi (War Media), warning: "What America waged in an aggression on Syria is a crossing of red lines. From now on we will respond with force to any aggressor or any breach of red lines from whoever it is, and America knows our ability to respond well."

Iranian supreme leader Ayatollah Ali Khamenei was less specific, but the message was plain when he told a Sunday meeting of his senior military commanders: "This is their last in a series of strategic errors ... which will definitely have backlash against their own interests."

But in the aftermath of the missile attack, Washington is under increased pressure from its allies, Congress and conservative media analysts to go harder against the Syrian regime.

"If this intervention is limited only to an air base, if it does not continue and if we don't remove the regime from heading Syria, then this would remain a cosmetic intervention," said Turkish foreign minister, Mesut Cavusoglu.

Briefing reporters, officials in Whitehall said that Britain was taking credit for helping to win traction in Washington for the idea that there could be no progress in Syria unless Assad and his family were removed.

US Senator Lindsey Graham, a longtime critic of Trump, told reporters at the weekend: "The [missile strike] is is better than doing nothing, a step in the right direction.

[But]"Does it change [Assad's] behaviour? We don't know yet if this attack will work or not."

Therein lies the risk to which Trump has exposed himself by firing off the missiles.

In demonstrating a willingness to go after the Syrian regime after two years of war in which the US has focused only on ISIS in Syria, Trump is under pressure to go further.

And he has demonstrated that he's a man who likes to please his audience.

He's already a more kinetic president than his predecessor.

New figures show that under Trump, the rate of US drone strikes in various conflicts is three times what it was under Barack Obama.

Amidst rising tensions over North Korea's nuclear program, Trump reportedly is considering returning American nuclear weapons to South Korea and/or killing the North's dictator Kim Jong-un.

A provocative plan for US forces to board Iranian ships in international waters was abandoned because it had leaked to the media.

Analysts are divided on what drives Moscow's Syria policy – is it so committed to Syria as a foothold in the Middle East and a seat at the international diplomatic table, or can it be swayed from that with the prospect of an easing or lifting of the burden of Western economic sanctions imposed after its annexation of Crimea.

But despite Tillerson's personal relationship with Putin and some of his trusted associates from his years as CEO of ExxonMobil, there's a view that ultimately progress will be dictated by the Putin-Trump relationship.

"It depends on whether Putin and Trump hit it off, not on anything Tillerson and Lavrov say," Michael McFaul, a former US ambassador to Russia, said. "Things will only happen as a result of direct personal, sustained contact between Putin and Trump.

"That's the way things work with Putin."

Maybe this whole business is a phase the administration is going through as it attempts to burnish a very indifferent performance in its first 100 days, a fast approaching milestone at which Americans traditionally pass judgment on a new president.

Paul Waldman, a commentator in The American Prospect, expects as much.

He writes: "So here's a prediction: within a matter of weeks or even days, Syria is going to fade from the American media and political agenda. On the ground there, civilians will keep dying, but here at home we'll go back to thinking of it as a terrible tragedy, but not something we can do much about (which isn't entirely wrong). And President Trump's missile strike will look less like a masterstroke of strength and resolve, and more like what it really was: a purely symbolic act with virtually no effect on the ground."