Ukraine and its European backers are seeking talks with U.S. President Donald Trump in an effort to protect their security interests ahead of his summit with Russian President Vladimir Putin later this week.

BERLIN—European leaders, fearful that President Trump will cut a deal with Vladimir Putin that undermines Ukraine and puts the continent’s security at risk, are planning another meeting with him ahead of a scheduled U.

European shares ticked lower on Monday, as investors refrained from making big bets ahead of an eventful week packed with tariff negotiations and ending with talks between the U.S. and Russia on the war in Ukraine.