Sri Lanka, April 19 -- U.S. President Donald Trump has warned that the United States will "take a pass" on further brokering peace talks between Russia and Ukraine if either Moscow or Kyiv obstructs efforts to reach a peace deal.

Speaking to reporters in the Oval Office on Friday, President Trump stated that while he desired a swift resolution, he was not expecting a truce within "a specific number of days."

His comments came shortly after U.S. Secretary of State Marco Rubio cautioned that the U.S. would withdraw from negotiations unless tangible progress was made within days.

"We're talking about here people dying. We're going to get it stopped, ideally," President Trump said regarding a potential agreement. "Now if, for some reason, ...