The United States has said it is increasingly concerned about Russian militarization along the Ukrainian border, as Ukrainian President Volodymyr Zelenskiy travels to the eastern front line.

The number of Russian troops on the border with the former Soviet republic is now higher “than at any time since 2014”, when war in eastern Ukraine broke out and Russia captured the Crimean region, White House spokesman Jen Psaki said in Washington.

“The United States is increasingly concerned about the recent escalation of Russian aggressions in eastern Ukraine, including Russian troop movements on the Ukrainian border,” Psaki said Thursday. “These are all deeply worrying signs.”

His comments came after the Ukrainian president’s visit to the eastern front line where fighting between the Ukrainian military and Russian-backed separatists has intensified in recent weeks.

Images released by Zelenskiy’s office showed the 43-year-old leader in the trenches dressed in a helmet and bulletproof vest, handing out rewards to Ukrainian soldiers and shaking their hands.

The long-running conflict in eastern, predominantly Russian-speaking Ukraine has claimed more than 13,000 lives since 2014.

German Chancellor Angela Merkel on Thursday called on Moscow to reduce the build-up of its troops.

During a phone call with Russian President Vladimir Putin, Merkel asked him to reduce “troop reinforcements” at the border “to defuse tensions,” his office said in a statement.

During his frontline visit, Zelenskiy thanked the soldiers “for protecting our land” and said “there is indeed an escalation” in eastern Ukraine.

“All commanders understand that snipers are targeting our men,” Zelenskiy said, adding that 26 Ukrainian soldiers have been killed since the start of the year, up from 50 in 2020.

In Moscow, the Kremlin pointer to relations with Ukraine and pro-Russian separatists, Dmitri Kozak, issued a new warning in Kiev on Thursday, saying that Russia may “have” to intervene to defend Russian speakers in the east. torn apart by war.

But, he added, an escalation would be “the beginning of the end of Ukraine”, describing this scenario for the former Soviet country as “not a bullet in the leg, but in the face”.

A new round of negotiations on Ukraine is scheduled for April 19, he added.

Fighting over the conflict, which erupted after Russia’s annexation of Crimea to Ukraine in 2014, subsided in 2020 with the establishment of a new ceasefire agreement in last july.

But clashes, mostly involving artillery and mortar fire, have resumed since the start of the year, with both sides blaming each other.

Ukrainian separatists are widely seen as enjoying Russian political and military support, which Moscow denies.

Ukraine last week accused Russia of massing thousands of troops on its northern and eastern borders as well as on the Crimean peninsula.

Along with France and Germany, Ukraine and Russia are part of the Norman format of countries that have sought to resolve the conflict since 2015 but have failed to end the fighting.

Western allies in Kiev have repeatedly warned Russia against further measures.

The Kremlin did not deny the troop movements but insisted that Moscow “was not threatening anyone”.

Zelenskiy this week urged NATO to speed up his country’s application to join the alliance, saying it was the only way to end the conflict.

Alliance members responded by calling on Kiev to continue military and defense reforms.

In a statement Thursday, Russian Foreign Ministry spokeswoman Maria Zakharova said NATO’s support for Ukraine “does not contribute to security” and “to the settlement of the conflict”.

She added that Moscow was concerned about “the financial and logistical support of the Ukrainian armed forces by NATO countries”, as well as the alliance providing lethal weapons and Western instructors training Ukrainian military personnel.

Analysts have been divided over Russia’s true intentions amid the latest escalation in tensions with Kiev, and some observers say Moscow may be testing Joe Biden’s commitment to defending Ukraine.

In his first call with Zelenskiy last week, Biden affirmed Washington’s “unwavering support” for Kiev in the conflict.