Don't call it a breakthrough, as there is still a long way to go before lasting peace.

But Tuesday's agreement between the US and Ukraine over a proposed temporary ceasefire in the war with Russia represents a remarkable change of course.

Just a week ago, the US suspended military aid and intelligence sharing with Ukraine in the aftermath of the bitter meeting between Volodymyr Zelensky and Donald Trump at the White House.

That US and Ukrainian diplomats were able to improve relations and chart a path forward serves as another illustration of how Trump, despite his apparent bluster and willingness to hurl insults, always appears open to further negotiations.

For him, in fact, the swagger and browbeating are often an integral part of the negotiating process.

But a strategy that involves a whirlwind of public threats and concessions is not without risks, as has been painfully apparent to the more than 60% of Americans with investments in the US stock market in recent weeks.

Major stock indexes continued to tumble on Tuesday after Trump escalated his war of words - and tariffs - with America's northern neighbour and largest trading partner, Canada.

In a caustic post on his Truth Social account, Trump said he would double impending tariffs on Canadian steel and aluminium in response to a planned Canadian surcharge on electricity bound for northern US states.

He said – again - that Canada becoming a US state is the "only thing that makes sense".

The aggressive style produced results within hours – the premier of Ontario, Doug Ford, backed down from the energy surcharge for now, and then Trump said he would no longer double the 25% tariffs coming into force on Wednesday.

But the ongoing trade dispute has erased trillions of dollars in US stock market wealth. And there is still the prospect of more tariffs - on Canada and other US trading partners - next month.

Meanwhile, despite Ukraine's acceptance of a time-limited truce if Russia plays its part, there is still no sign of the mineral rights deal which would give the US a share of future Ukrainian mining revenues.

Trump has made clear how much he wants this, and it could be a stumbling block down the road.

There is also no indication of whether Russia will accept the 30-day ceasefire proposal. It is also unclear what the Trump team is willing to do to convince Vladimir Putin to say yes.

Will the same playbook work? Or will Trump have to find another tool in his negotiating kit?

There is, however, clear progress towards Trump's promise, repeated throughout much of last year's presidential campaign, that he is the one who can end the war after three years.

He has chosen to perform a high-wire act where success could bring peace and prosperity. The price of failure, however, will be measured in lives lost.