WASHINGTON • The US Defence Department has urged Russia to make clear its intentions regarding a build-up of military forces along Ukraine's south-east border and in Crimea.
Pentagon spokesman John Kirby said Russia had not announced, as is traditional, that it was conducting military exercises, leaving its intentions ambiguous and firing up tensions in the region.
"We call on Russia to make their intentions more clear as to what they're doing with this array of forces along the border," Mr Kirby told reporters in a briefing on Tuesday. "What's important is... to de-escalate the tensions along that border."
All sides need to abide by the 2014-2015 Minsk agreements on the Ukraine conflict with Russia-aligned rebels, "and to bring the temperature down and to de-escalate", he added.
Mr Kirby would not give any details of what the United States knows of the deployments. Unconfirmed videos on social media show significant amounts of Russian armour being ferried into the area, together with military vehicles.
Mr Kirby said the biggest US concern is the increased Russian presence on Ukraine's south-east border and in Crimea, the Ukraine territory that Moscow seized in 2014.
"We continue to see Russian forces arrayed along the border with Ukraine, in Crimea specifically... and we're monitoring that very, very closely," he said.
On Monday, State Department spokesman Ned Price said Washington remained very concerned about "escalating Russian aggression in eastern Ukraine".
"At the highest levels of government, literally, across multiple institutions, we have sent that message very clearly to our Ukrainian counterparts, and implicitly to the Russians as well, that we stand by Kiev, we stand by our partner Ukraine, in the face of this intimidation and aggression," Mr Price said.
President Volodymyr Zelensky called on Nato on Tuesday to lay out a path for Ukraine to join the Western military alliance, after days in which Russia had massed troops near the conflict-hit Donbass region.
Mr Zelensky's comments drew an immediate rebuke from Moscow, which said Kiev's approach to Nato could further inflame the situation in Donbass, where violence has increased in recent days.
The restrained response to Mr Zelinsky's request by the United States - which has strongly supported Ukraine as it faces the Russian military build-up - suggested a desire to avoid unnecessarily antagonising the Kremlin any further.
White House press secretary Jen Psaki noted that Ukraine has long aspired to join Nato and that Washington and Kiev have been discussing the issue.
Mr Price restated the US policy of supporting an "open door" to Nato for countries meeting "the standard for membership". But Ukraine, he said, still must "implement the... reforms necessary to build a more stable, democratic, prosperous and free country".
The Pentagon has released a statement noting that the alliance in 2018 reaffirmed a decision that Ukraine "will" become a member, adding that any questions on the matter be addressed to Nato.
Ukraine also said on Tuesday that it wanted to move ongoing peace talks away from the Belarusian capital Minsk, saying Belarus was too much under the influence of Russia.
"We don't know where (the talks) could be relocated. This is the subject of discussion," Ukraine's Deputy Prime Minister Oleksiy Reznikov said.
Russian-backed separatists have, since 2014, been fighting against Ukrainian forces in the Donbass.
AGENCE FRANCE-PRESSE, REUTERS