Russian President Vladimir Putin on Tuesday stepped up private and public calls on Western leaders to end the eastward expansion of NATO. In phone conversations with Finnish President Sauli Niinisto and then later with French President Emmanuel Macron, Putin called for "immediate" negotiations with NATO and the US.

"The Russian president emphasized the importance of immediately launching international negotiations to develop legally fixed guarantees that would prevent any further NATO expansion to the east and the deployment of weapons to neighboring states, primarily in Ukraine, that threaten Russia," read a Kremlin statement released on Tuesday.

Putin's calls reiterated similar statements made in recent discussions with US President Joe Biden and UK Prime Minister Boris Johnson.

How does Moscow see NATO membership for Ukraine?

Russia has clearly articulated that neighboring Ukraine's aspirations to join NATO — a Western military alliance — cross a red line. The Kremlin says it is also concerned about NATO members setting up military training operations in Ukraine — warning that it would give Western militaries a foothold at its doorstep even if Ukraine failed to join the alliance.

Recent reports of a buildup of between 75,000-100,000 Russian troops along the Ukraine border have caused tensions between Moscow and the West to flare once again in recent weeks, with many observers fearing Moscow could be planning an invasion.

Moscow denies such accusations claiming its stance is purely defensive, instead blaming Ukraine, NATO and Western powers for the highly charged situation.  

Western intelligence services have suggested Moscow's troop buildups may represent a threat scenario designed to create bargaining leverage.

In a video conference last week, US President Joe Biden warned Putin of "sanctions like he's never seen" should Russia attack its neighbor. The EU and G7 have also met to discuss actions to be taken in the event of Russian aggression.

Will Russia attack Ukraine?

On Monday, Russian Deputy Foreign Minister Sergey Ryabkov was matter of fact about Moscow's course of action should a stalemate on NATO's eastern expansion persist: "The lack of progress toward a political-diplomatic solution to this problem will lead to the fact that we will respond militarily," he told the RIA Novosti state news agency.  

Western military activity in the region, namely the presence of French warships in the Black Sea and Ukrainian troop buildups along the border, have only pushed tensions further. Moscow claims it was forced to scramble fighter jets to escort French and US military aircraft from the area last week.

President Putin also accused Kyiv of increasingly using "heavy weapons and attack drones" against rebels in eastern Ukraine during his call with Finnish President Niinsto.     

Russia annexed Ukraine's Crimean peninsula on the Black Sea in 2014 and has supported pro-Russian insurgents fighting Kyiv in eastern Ukraine since that time. The conflict has claimed more than 13,000 lives.

js/fb (AFP, dpa, Reuters)