U.S. President Donald Trump said on Tuesday that he regarded his Russian counterpart Vladimir Putin as "a competitor," a claim coming days ahead of his expected meeting with the Russian president in Finland's capital Helsinki.

Trump was leaving the White House for his week-long Europe trip when asked by reporters if Putin is a "friend or foe."

"I really can't say right now," replied Trump, adding that "as far as I'm concerned, a competitor."

Trump was heading to Brussels to attend a North Atlantic Treaty Organization (NATO) summit slated for July 11-12, after which he will visit Britain and then meet Putin in Helsinki on Monday.

"Frankly, Putin may be the easiest of them all," noted the U.S. president comparing his Europe schedules.

Ties between Washington and Moscow have slumped into a new low over Russia's alleged meddling in the U.S. 2016 elections, Syria and Ukraine issues and their diplomatic disputes among others.

In a background briefing last week, U.S. Ambassador to Russia Jon Huntsman told reporters that issues concerning strategic balance and arms control will be "prominent" on the agenda during the summit.

Meanwhile, Ukraine and Syria issues, as well as the alleged election meddling, will also "enter the picture," the ambassador added.