Amid allegations from Ukraine that Russia has been massing troops at their shared border, Russian Foreign Minister Sergei Lavrov has warned that any attempts at a "new war" in eastern Ukraine would end up destroying that country.
The threat lands as Moscow and Kyiv trade blame over a recent spike in violence in the yearslong conflict between Ukrainian government forces and Russia-backed separatists.
Kyiv claims the separatists are "systematically violating a cease-fire” agreed in July and blames Russia for a purported build-up of Russian military forces near their shared border -- an accusation rejected by the Kremlin.
Ukrainian Foreign Minister Dmytro Kuleba tweeted on April 1 that he had spoken with Helga Schmid, the secretary-general of the Organization for Security and Cooperation in Europe (OSCE), “on Russia’s systemic aggravation of security situation in the east or Ukraine & in Crimea."
He also welcomed this week’s extension for another year of the OSCE’s Special Monitoring Mission to Ukraine, saying the pan-European organization “should closely follow Russian moves.”
In an interview aired on Channel One later in the day, Lavrov quoted Russian President Vladimir Putin as saying "not so long ago, and the statement remains topical today, too, [that] those who attempt to start a new war in Donbas will ruin Ukraine."
Kremlin spokesman Dmitry Peskov said that Russia was "moving troops within its own territory at its own discretion, and this shouldn't concern anyone."
"We need to stay on guard" in the face of "intense activity" of NATO troops "on the perimeter of Russian borders," he told reporters.
Following Lavrov and Peskov's statements, U.S. State Department spokesman Ned Price warned Moscow against "intimidating" Ukraine.
"We're absolutely concerned by recent escalations of Russian aggressive and provocative actions in eastern Ukraine," Ned Price told reporters.
"What we would object to are aggressive actions that have an intent of intimidating, of threatening, our partner Ukraine."
Russia, which forcibly annexed Crimea in 2014 after long denying the presence of its troops there, has consistently denied involvement in the fighting in eastern Ukraine's Luhansk and Donetsk regions despite significant evidence to the contrary.
The OSCE’s Ukraine mission has reported hundreds of cease-fire violations in Donetsk and Luhansk in recent days in a simmering conflict that has claimed more than 13,000 lives since April 2014.
Russia annexed Crimea in March 2014 after sending in troops and staging a referendum denounced as illegitimate by at least 100 countries after Moscow-friendly Ukrainian President Viktor Yanukovych was ousted amid a wave of public protests.
In an address to the OSCE Permanent Council in Vienna on March 31, U.S. charge d’affaires Courtney Austrian welcomed the extension of the OSCE mission's mandate, and reaffirmed Washington’s unwavering commitment to Ukraine’s "sovereignty and territorial integrity within its internationally recognized borders, including its territorial waters."
Austrian called "on Ukraine, Russia, and the forces Russia arms, trains, leads, and fights alongside, to ensure that the SMM has unfettered movement throughout the entire territory of Ukraine," including Crimea, and to "guarantee the safety and security" of international monitors while they carry out their duties.
"Attacks, threats, and intimidation of any kind against SMM monitors," as well as "attempts to interfere" with their operations are "unacceptable, inconsistent with [the mission’s] mandate, and must end."
Also on March 31,, U.S. General Mark Milley, chairman of the U.S. Joint Chiefs of Staff, spoke with General Valery Gerasimov, the Russian Armed Forces chief of staff, and General Ruslan Khomchak, chief of the general staff of the Ukrainian Armed Forces, the Pentagon said.
Defense Department spokesman John Kirby later said that "Russia's destabilizing actions undermine the de-escalation intentions that had been achieved through an OSCE-brokered [cease-fire] agreement back in July of last year."
"We are discussing our concerns about this increase in tensions and cease-fire violations and regional tensions with NATO allies," Kirby told a briefing.
The Ukrainian military said on March 26 that four Ukrainian soldiers were killed and two others wounded in shelling in Donetsk, bringing the total number of Ukrainian servicemen reported killed since December to 19, according to AFP.
Khomchak on March 30 accused Moscow of building up its military presence near the Ukraine-Russia border “under the guise of preparing for strategic exercises.”
The buildup is in addition to thousands of troops in combat brigades, regiments, and supply units deployed in Donetsk and Luhansk with the support of Russian regular troops, the Ukrainian Army chief said in an interview with Voice of America.
“We are preparing for all possible provocations and reactions to the actions of the enemy,” Khomchak said.
Khomchak first made the accusations of a Russian military buildup in a speech to Ukraine's parliament on March 30.
The comments drew a response from Russian President Vladimir Putin during a March 30 videoconference call with French President Emmanuel Macron and German Chancellor Angela Merkel, the Kremlin said.
Putin placed the blame for tensions on Ukraine and urged Kyiv to enter into direct dialogue with local separatist forces.
A statement from the French presidency indicated that during the videoconference call Macron and Merkel urged Putin to take steps to de-escalate.
"The need for Russia to make a determined commitment to stabilize the cease-fire in Ukraine and work out a way out of the crisis while respecting the Minsk Agreements was underlined," the Elysee Palace said.
Germany, Russia, France, and Ukraine are part of the so-called Normandy Format set up to try to resolve the Ukraine conflict.