DONETSK, Ukraine - Ukraine's acting president is ordering security forces to resume operations in the country's east, claiming that the body of a politician from his political party was found with signs of torture after being abducted, according to reports.
Additionally, the Ukrainian Defense Ministry says a military aircraft was struck by gunfire over one of the tensest cities in the region.
If confirmed, it would represent a grim turn in the crisis in Ukraine. The developments Tuesday raised fears over whether last week's international agreement on easing Ukraine's crisis can succeed. The agreement calls for all sides to refrain from violence and for demonstrators to vacate public buildings.
There had already been doubts about the agreement's ability to succeed, after a deadly shootout at a checkpoint on Easter, as well as the revelation of Ukraine's alleged photographic "proof" that Russian special forces were sowing unrest in the country's east.
Pro-Russia insurgents in eastern Ukraine have rejected the agreement, arguing they were not party to it, even though Russia was a key negotiator.
Ukraine suspended its so-called anti-terrorist operation in the east after the agreement. President Oleksandr Turchynov said Tuesday it must be resumed.
The acting president said in a statement that two "brutally tortured" bodies had been found near the city of Slavyansk, which is in the hands of pro-Russian militants, according to Reuters. One was allegedly that of Volodymyr Rybak, a member of Turchinov's Batkivshchyna party, who had recently been abducted by "terrorists," the BBC reports.
"These crimes are being carried out with the full support and indulgence of the Russian Federation," Turchynov said, according to Reuters. "I call on the security agencies to relaunch and carry out effective anti-terrorist measures, with the aim of protecting Ukrainian citizens living in eastern Ukraine from terrorists."
The Defense Ministry said gunfire hit an observation plane over the city of Slovyansk, but landed safely without injuries.
After meeting with leaders in Kiev Tuesday, Vice President Joe Biden called on Russia to "stop talking and start acting" to defuse the crisis.
The Obama administration has attempted to strike a delicate balance between working with and rebuffing the Russians. While Biden said he hopes for "peaceful relations" between Ukraine and Russia, he added the U.S. "will never recognize Russia's illegal occupation of Crimea."
Biden also went on to detail the material support the U.S. is giving Ukraine.
"We're providing communications gear, bomb disposal technology, transportation and engineering equipment for Ukraine to protect against infiltrators and deal with explosive threats," Biden said. "And our security support now totals nearly $20 million."
On the same day that Biden concluded his visit to Ukraine, the Pentagon announced it is sending a company of paratroopers from Vicenza, Italy, to conduct an exercise in Poland, CBS News correspondent David Martin reports. Company-sized exercises will also take place in Estonia, Latvia and Lithuania. Troops should all be in place by this weekend, and the exercise could last a month or so and then other companies could come in to conduct another cycle of exercises to provide a "persistent" - as opposed to "permanent" - presence. Troops arrive in Poland tomorrow.