The United States will abandon efforts to end the war in Ukraine if it proves impossible to broker meaningful progress in the next several days, Secretary of State Marco Rubio said as he departed Paris on Friday a day after meeting with President Emmanuel Macron of France.

“If it is not possible to end the war in Ukraine, we need to move on,” Mr. Rubio told reporters, adding that the Trump administration would decide “in a matter of days whether or not this is doable in the next few weeks.”

It was not clear from Mr. Rubio’s remarks whether he meant that the United States would merely abandon its effort to reach a 30-day cease-fire between Russia and Ukraine or abandon Washington’s commitments to Ukraine altogether.

But his remarks ratcheted up pressure on both sides to end the war and appeared intended to inject urgency into European efforts to prod Volodymyr Zelensky, the Ukrainian president, toward compromise.

While the United States is Russia’s chief interlocutor in the negotiations, Europe has far greater sway over Mr. Zelensky. President Trump said on Thursday that he was “not a big fan” of the Ukrainian leader.

Mr. Rubio said Mr. Trump “has spent 87 days at the highest level of this government repeatedly making efforts to bring this war to an end. We are now reaching a point when we need to decide and determine whether this is even possible or not.”

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