U.S. Secretary of State Marco Rubio said President Donald Trump hasn’t yet imposed penalties on Russia over its ongoing war with Ukraine because the White House is still hoping diplomacy can end the war.

“The minute you start doing that kind of stuff, you’re walking away from it,” Rubio said Sunday on NBC’s ‘Meet the Press.’

Rubio said that the coming week will be “very critical” for the White House as it makes a “determination about whether this is an endeavor that we want to continue to be involved in.”

“There are reasons to be optimistic, but there are reasons to be realistic,” Rubio said, adding: “We’re close, but we’re not close enough.”

“Throughout this process, it’s about determining, do both sides really want peace and how close are they or how far apart they are after 90 days of effort here … that’s what we’re trying to determine this week,” Rubio said of negotiations.

Rubio’s comments come as Trump is ramping up pressure on Russia and Ukraine to reach a peace deal. Trump met Saturday with Ukrainian President Volodymyr Zelenskyy, just before floating the possibility of tougher sanctions against Moscow.

Rubio said that Trump has “made real progress” in nearing an end to the war, but “those last couple steps of this journey were always going to be the hardest ones, and it needs to happen soon.”

“We cannot continue, as I said, to dedicate time and resources to this effort if it’s not going to come to fruition,” he added.

Trump on Saturday questioned whether Russian President Vladimir Putin wants to “stop the war” against Ukraine.

“It makes me think that maybe he doesn’t want to stop the war, he’s just tapping me along, and has to be dealt with differently, through “Banking” or “Secondary Sanctions?” Too many people are dying!!!” Trump wrote on Truth Social.

His post came just after he had a private meeting with Zelenskyy in Rome, which the White House described as a “productive discussion.”