Updated

Russian President Vladimir Putin is flying to Mongolia on Wednesday for a working visit amid soaring tensions with Washington and NATO over a Kremlin-backed offensive in Ukraine.

Putin is due to arrive in the Mongolian capital of Ulan Bator for afternoon talks with Mongolian President Elbegdorj Tsakhia. The two are to oversee the signing of trade and transport agreements before Putin departs at 6 p.m. (1000 GMT).

Moscow firmly controlled Mongolia during the Cold War and retains considerable influence over this vast landlocked nation sandwiched between Russia and China. Mongolia relies on Russia for almost all of its gasoline and diesel fuel and much of its electricity.

Moscow also holds a 51 percent stake in Mongolia's railway and a 49 percent stake in its largest state-owned copper mine.

With Western investment declining, Mongolia is turning increasingly to China and Russia to support its mining and animal herding-based economy, while also maintaining close ties with the U.S. and others as a counterbalance.

Chinese President Xi Jinping paid a state visit last month, during which the sides pledged to almost double their annual two-way trade to $10 billion by 2020.

Putin's visit is his third since he first became Russia's president in 2000. It comes as Ukrainian officials say their country's armed forces are now locked in a conflict with not only Moscow-backed separatists, but also the Russian army, although Putin has denied that his forces are invading Ukraine.

In response, President Barack Obama and Western allies are due to approve plans this week to position at least 4,000 troops and military equipment in Eastern Europe to reassure nervous NATO states near the Russian border.