U.S. President Donald Trump is taking Teddy Roosevelt’s maxim – “Speak softly and carry a big stick” – and putting it into a higher gear. He talks loudly while brandishing a heavy stick on the world stage.

He is challenging China overtly with a rolling onslaught of tariffs and shows no sign of blinking, nor any obvious concern about the negative fallout on the global economy. Mr. Trump also intends to withdraw from a 180-year-old postal-services treaty that he believes gives Chinese shippers unfair advantages.

Mr. Trump jettisoned the nuclear agreement with Iran and is on the verge of levying sanctions on Iran’s oil exports and on its capacity to finance business globally. He is cajoling others with overt threats of American sanctions against those companies who do not follow suit.

By signalling his intention to withdraw from the Intermediate-Range Nuclear Forces (INF) agreement because of Russian non-compliance, Mr. Trump contradicts the notion that he is soft or accommodating on Russia and belies the charm offensive he evinced toward Russian President Vladimir Putin in Helsinki. He is confounding critics and allies alike. National Security Adviser John Bolton, no shrinking violet himself, was dispatched to Moscow to explain this INF move to his equally wily counterpart, Sergei Lavrov, as well as to President Putin. He suggested that the announcement was really intended to initiate a renegotiation – a consistent Trump tactic – one that may also involve some degree of alliance consultation.

While Mr. Trump’s actions are more instinctual or impulsive than strategic, there may be more to the INF announcement than meets the eye. It may, in fact, be directed as much at China as at Russia. China is not a signatory to the INF, but is rapidly expanding its capacity for such weapons. Securing a broader INF deal may be the real U.S. objective.

Less noticed than these actions was a speech to the Atlantic Council last week by A. Wess Mitchell, U.S. Assistant Secretary of State for European and Eurasian Affairs. He described the competition for influence in the world as ”the central task of U.S. foreign policy.” Mr. Mitchell castigated overt efforts – economic and military – by Russia and China to undermine stability in Central and Eastern Europe. “Today it is the national sovereignty and territorial integrity of frontier states like Ukraine, Georgia and even Belarus, that offer the surest bulwark against Russian neo-imperialism … The idea that a large, authoritarian power like Russia or China would become sincere champions of true national independence is unthinkable. Both operate on authoritarian, geopolitical traditions antithetical to the freedom of nations.”

Mr. Mitchell explicitly warned that Western Europeans “cannot continue to deepen energy dependence on the same Russia that America defends them against.” German Chancellor Angela Merkel got the message. After constant badgering from Washington about Germany’s over-dependence on gas imports from Russia, she announced that facilities would soon be built on the German coast to accommodate LNG imports from the U.S.

Mr. Putin castigated recent U.S. behaviour as a “huge strategic mistake, typical of any empire, one which believes itself so strong and stable that there will be no negative consequences. But, they will come sooner or later.”

Thanks to the barbaric assassination of Jamal Khashoggi, Saudi Arabia now poses a more immediate challenge to the U.S. Substantial strategic and commercial linkages are at stake and Mr. Trump has made an extraordinary investment in close personal relations with Crown Prince Mohammed bin Salman, whose involvement in the murder is subject to intensive speculation. The outrageous nature of the killing is exceeded only by the patent stupidity of the perpetrators. Bipartisan angst is mounting in Congress against the Crown Prince and Mr. Trump will have to thread a fine needle in finding the right response. Invoking sanctions against some individuals will not suffice. He will straddle as best and as long as he can probably with his customary, enigmatic reflex – “We’ll see what happens” – but considerations in Washington about regional stability and Saudi Arabia’s enormous oil reserves are likely to prevail.

The Master of Disruption is battling on many fronts these days. Any concern that the U.S. may be diminishing its role or influence in world affairs is more than offset by actions that are unconventional and derived bluntly from the “America First” catechism. Gone are the days of more nuanced U.S. global leadership. What we now see is a full-throated claim for recognition and respect from allies and foes alike in a more turbulent world.

It is a high-wire act with risks as daunting as the potential advantages. Unlike his predecessor, Mr. Trump is not averse to risk on global or domestic affairs. He revels in rhetorical combat that matches his election campaign salvos. Less clear are the implications for global stability.