A spokeswoman with the pro-Russian insurgents in Sloviansk, Ukraine, confirmed on Wednesday that they have captured Vice News reporter Simon Ostrovsky and are holding him hostage.

"He's with us. He's fine," Stella Khorosheva told The Associated Press, adding, "(We) need to be careful because this is not the first time we're dealing with spies."

Khorosheva also told The Daily Beast that Ostrovsky is being held according to the "laws of war" because "he was not reporting in a correct way."

Perhaps more worrisome, the spokeswoman said that the militants had planned the journalist's kidnapping.

“We knew where he was going and the men manning the checkpoint were told to look out for him," Khorosheva said of Ostrovsky.

Sloviansk's self-declared "mayor" told a journalist that he was holding the Vice News reporter "as is their right, will release him whenever he deems fit."

Mayor says that they are holding Simon as is their right, will release him whenever he deems fit. — GrahamWPhillips (@GrahamWP_UK) April 23, 2014

Speaking to the Russian outlet Gazeta.ru, Vyacheslav Ponomarev said, "We won't release Ostrovsky any time soon. We need hostages — small change to trade with Kiev."

Time reported Wednesday morning that Ostrovsky was part of a group of journalists that had been detained Monday night after being stopped at a checkpoint by armed separatists. The others were freed within an hour. Ostrovsky remains in captivity.

Vice News told Mashable on Tuesday that they were aware of Ostrovsky's situation and were working with the U.S. State Department to secure his release.

We are aware of @SimonOstrovsky's situation and are working to ensure the safety and security of our friend and colleague. — VICE News (@vicenews) April 22, 2014

State Department spokeswoman Jen Psaki condemned the journalist's kidnapping in a statement issued later on Tuesday. “We are deeply concerned about the reports of a kidnapping of a U.S. citizen journalist in Slovyansk [sic], Ukraine, reportedly at the hands of pro-Russian separatists," Psaki said. "We condemn any such actions, and all recent hostage takings in eastern Ukraine, which directly violate commitments made in the Geneva joint statement. We call on Russia to use its influence with these groups to secure the immediate and safe release of all hostages in eastern Ukraine. We have also raised our concerns with Ukrainian officials as they work with local authorities to try to de-escalate the security situation in and around Slovyansk.”

.@StateDeptSpox: We are deeply concerned about the reports of a kidnapping of a US citizen journalist in Slovyansk, #Ukraine. — Department of State (@StateDept) April 23, 2014

Sixteen people have been kidnapped in Eastern Ukraine over the past week, the Kiev Post reports. Some of them have since been released. Two were found dead.

The escalating tensions in the region have led Ukraine's interim president, Oleksandr Turchynov, to resume an anti-terrorism operation in the region.

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“Terrorists … who have taken hostages in Donetsk region overstepped the limits when they started to torture and kill patriots of Ukraine," Turchynov said. "They dared to toss a challenge not just to our country, but to the whole world as well… following the decisions adopted in Geneva,” he added, referring to the meeting in Geneva among the U.S., EU, Ukraine and Russia last week, during which the nations hashed out a tentative agreement to de-escalate the crisis.

Ostrovsky's most recent tweets were sent from a press conference on Monday in the east Ukrainian city of Sloviansk, where the town's acting mayor warned a journalist over a "provocative" question.

"Now he's not letting reporters leave the press conference: 'you'll go as you came in. In a group.' That's one way to guarantee coverage," Ostrovsky tweeted.

Now he's not letting reporters leave the press conference: "you'll go as you came in. In a group." That's one way to guarantee coverage. — Simon Ostrovsky (@SimonOstrovsky) April 21, 2014

Since his capture, the journalist has been widely praised on Twitter and Reddit for his dogged reporting on the deescalating situation in the country.

His most recent report, Dispatch 28, came as Ukraine launched its first anti-terror campaign to recapture the cities being occupied by pro-Russia protesters. "So far, the campaign hasn't been going so well," Vice wrote in the video's description.

Watch it here: