U.S. President Donald Trump repeatedly said during his successful campaign for a second term that he could end the war in Ukraine “in 24 hours.”

But since his Jan. 20 inauguration, the road to a peace deal has been fraught with changing dynamics among Trump, Ukrainian President Volodymyr Zelenskyy and Russian President Vladimir Putin.

A summit between Trump and Putin set for Friday in Alaska could now be a pivotal moment in the 3 1/2-year-old war.

“At the end of that meeting, probably the first two minutes, I’ll know exactly whether or not a deal can be made,” Trump said Monday.

Trump’s rhetoric toward both Zelenskyy and Putin has evolved this year.

At the start of his second term, Trump was conciliatory toward Putin, for whom he has long shown admiration.

But as Putin remained intransigent and rejected an unconditional truce proposed by Trump, the Republican leader has expressed increasing exasperation with the Russian leader, criticizing him for his unbudging stance on U.S.-led peace efforts and for prolonging the war.

Until recently, Trump repeatedly said Russia seemed more willing than Ukraine to get a deal done.

Trump appears to have softened toward Zelenskyy after a February confrontation in the Oval Office.

And, in a reversal, he promised at some point to provide Ukraine with badly needed Patriot air defense missiles under a deal that would see NATO allies in Europe deliver them from their stock, to be replaced by future U.S. supplies.