Russia is threatening to reject President Donald Trump's Ukraine peace plan unless "key understandings" from his Alaska summit with President Putin are upheld.

The Russian leader said he felt Washington was taking his position into account, but that some things still needed to be discussed when a U.S. delegation visits Moscow next week.

As Washington ramps up its negotiations with Ukraine and Russia and U.S. President Donald Trump expresses optimism that a peace deal could be close, there are still some very critical and contentious issues on which Kyiv and Moscow are in deep disagreement.

During President Donald Trump’s contentious Oval Office meeting last month with Ukrainian President Volodymyr Zelensky, he told his top aides to push for a deal that would successfully halt Russia’s nearly four-year war in Ukraine,

A Putin ally has called for more detail in Trump's peace plan for Ukraine. Follow Newsweek's live coverage of the war.

Amid this opposition, a series of meetings is expected. Today, there will be a meeting between US and Russian officials in Abu Dhabi, and a virtual one between the coalition of the willing, hosted by Keir Starmer and Emmanuel Macron. Ukraine's official also says they expect a meeting between Volodymyr Zelensky and Donald Trump in the next few days.

Turkey's defence ministry said on Thursday that a ceasefire between Ukraine and Russia must be achieved first before any discussions can take place on possible troop deployment for a potential reassurance force.

In Asia, Chinese leader Xi Jinping is attempting to steer Trump toward abandoning Taiwan in exchange for an expansive U.S.-China trade accord, a key Trump goal. China claims the self-ruled island as its own and hasn’t ruled out taking it by force.

Officials say progress was made in urgent weekend talks on amending the U.S. peace proposal for Ukraine that many saw as favoring Russia. But the Kremlin on Monday said it hadn't seen the changes.

The war in Ukraine has been raging for almost four years; 11 if you start with Crimea’s annexation in 2014. So many predictions have proved wrong along the way: Russia will win within a week. Ukraine is winning, against the odds. Western sanctions will bleed Russia dry and force it to the negotiating table.

The original U.S. plan, which Ukrainians and Europeans said was too favorable to Russia, was modified in negotiations in Geneva last weekend.