President Donald Trump and Russian President Vladimir Putin during a joint press conference after their July summit in Helsinki, Finland. Photo: Chris McGrath/Getty Images

President Trump told the Washington Post today he's considering cancelling a meeting later this week with Vladimir Putin after Russia seized three Ukrainian ships Sunday off the coast of Crimea. Ukrainian President Petro Poroshenko, meanwhile, told NBC News that he's asking Trump to make a demand of Putin in the meeting: "Get out of Ukraine."

The backdrop: Ukraine's parliament voted yesterday to impose martial law for 30 days in areas under threat from Russia, which is still holding 24 Ukrainian sailors after Sunday's incident. Poroshenko told CNN Russia was concentrating troops near the border, and the order was needed to "move troops more easily" and "defend our territorial integrity." The conflict is now likely to play a central role in the Trump-Putin meeting, assuming it goes ahead.

The details: As Alina Polyakova of Brookings writes for Axios Expert Voices, the attack on naval vessels now “opens a new front in Russia’s four-year aggression against Ukraine, which includes the ongoing land war in Ukraine's east and the occupation of Crimea."

  • Trump told the Post he's awaiting a report from his national security team about the incident, and said: “I don’t like that aggression. I don’t want that aggression at all."
  • Poroshenko told NBC that his military is prepared to impose "a huge price" on Russia if war comes. He also said "I count on the United States" to support Ukraine.
  • The Ukrainian president also told CNN that Secretary of State Mike Pompeo had pledged “full assistance, including military assistance."

All of that comes after President Trump initially seemed to place blame on both sides in the conflict, saying: “we do not like what's happening either way.”

Go deeper:

Go deeper

40 mins ago - Podcasts

The art and business of political polling

The election is just eight days away, and it’s not just the candidates whose futures are on the line. Political pollsters, four years after wrongly predicting a Hillary Clinton presidency, are viewing it as their own judgment day.

Axios Re:Cap digs into the polls, and what pollsters have changed since 2016, with former FiveThirtyEight writer and current CNN politics analyst Harry Enten.

Twitter launches warnings on election misinformation and delays

Photo: courtesy of Twitter

Twitter will start pinning notices to the top of all U.S. Twitter users’ timelines warning that results in next week’s election may be delayed and that they may encounter misinformation on mail-in voting.

Why it matters: Delayed election results are expected across many states that are handling unprecedented amounts of absentee and mailed ballots, which President Trump has baselessly called "very dangerous" and "corrupt."

Miriam Kramer, author of Space
3 hours ago - Science

NASA confirms water exists on sunny parts of the Moon

Photo: NASA/JPL/USGS

Water on the Moon might be more easily accessible than previously thought, opening up new possible avenues for future human exploration, according to a new study.

Why it matters: NASA is aiming to send people back to the Moon as part of its Artemis program by 2024, with plans to eventually create a sustainable presence on the lunar surface. That sustainability relies on mining the moon for its resources, like water.