The US President Barack Obama called on NATO's Europe members to do their fair share of defense spending, as he announced more aircraft and soldiers would be deployed to the Baltic region.

He was speaking from the Estonian capital, Tallinn, where he arrived on Wednesday in what is seen as a symbolic show of solidarity with Eastern Europe. NATO allies, such as Estonia, are nervous about the Russian-backed military intervention in Ukraine and fear they could be the next target.

Obama said the US had a duty under NATO's charter to the alliance's collective defense.

"It is unbreakable, it is unwavering, it is eternal. And Estonia will never stand alone," Obama said at a news conference with Estonian President Toomas Hendrik Ilves (pictured above).

Around 150 US soldiers are currently stationed in Estonia. Obama said Estonia's Amari Air Base would be an ideal location to base additional forces, but did not give detail of how many. His plan must still be approved by the US Congress.

His visit to Estonia comes a day ahead of a NATO summit in Newport, Wales, where Obama and Western allies will approve plans to position at least 4,000 troops and military equipment in Eastern Europe.

It comes as Ukraine and Russia announced conflicting details of an apparent truce, which Ukraine intially labeled a "ceasefire." Russia issued an immediate denial.

Obama said it was "too early to tell" how serious the Ukraine reports were. He also condemned the brutal murder of US journalist Steven Sotloff by an Islamic State militant.

On Tuesday, Obama ordered 350 US troops to be sent to Baghdad, to protect US embassy and staff in the Iraqi capital.

jr/ksb (AP, Reuters, dpa)