Putin has barely shifted on Ukraine - and any Russian reluctance to peace plan will be a test for Trump

Amid the forward momentum, it's telling that Trump touched the brakes.

"He doesn't have anything until I approve it," is how he trailed Volodymyr Zelenskyy's upcoming visit to Mar-a-Lago. The Ukrainian leader has spoken of a peace plan that's "90% ready" but, as the guest markets its potential, the host isn't buying - yet, at least.

Any breakthrough breaks down on Russian refusal and Donald Trump needs no reminding - it's the evergreen reality that has undermined peace efforts and tested his diplomatic muscle with Moscow, often with unflattering results. Zelenskyy and coalition allies have talked him back from the brink - a sell-out, as they saw it, when the US floated a 28-point plan that read like a Russian wish list.

The 20-point version crafted in Kyiv includes compromise and Zelenskyy talks of a "good conversation" with Trump's envoy Steve Witkoff and son-in-law Jared Kushner, in teeing up a tete-a-tete with the man himself. So far, so promising - but relative silence from Moscow screams otherwise.

Russian officials have made some optimistic noises but they have been measured and minimal. Vladimir Putin has barely shifted from his original position on Ukraine and there's limited expectation that will change this weekend.

Why would it? This is a Russian leader basking in the bonhomie of a president reshaping US relations to Moscow's advantage and he senses opportunity to pursue territorial ambitions. Antagonism between the US and European allies is but another benefit to Putin of things as they are.

Read more:Peace talks: What are the main issues remaining? In such circumstances, a framework proposal that locks down his ambition, long-term, won't necessarily land well in Moscow. Is that why he played down the significance of the Zelenskyy plan? Not for the first time, any Russian reluctance will be a test for Donald Trump - of strength, diplomacy, and of where his loyalties lie..