Ukrainian lawmakers on Tuesday dismissed acting defense minister Igor Tenyukh over his handling of the Crimea crisis following Russia's annexation of the Black Sea peninsula. (Anatolii Stepanov/AFP/Getty Images)

Ukraine fired its defense minister Tuesday, a major test of a new government trying to recover from defeat at Russia’s hands in Crimea while attempting to project enough self-confidence to win the people’s trust.

Mistakes have been and will be made, Andriy Parubiy, secretary of the National Security and Defense Council, said in an interview Tuesday, but the new government is not afraid to fix them.

“Now is the time to speak the truth to society,” he said. “This is the only way to make this government stronger.”

Extraordinary strength is required, he said, because Russian President Vladi­mir Putin wants nothing more than to take all of Ukraine. “His goal is to delegitimize the government,” Parubiy said.

The defense minister, Igor Tenyukh, who was accused of being indecisive and slow to give orders to Ukrainian military units in Crimea, submitted his resignation to parliament Tuesday. He was replaced by Gen. Mykhaylo Koval, who previously served with the border guards in Crimea and was briefly kidnapped there this month.

1 of 35 Full Screen Autoplay Close March 28, 2014 March 27, 2014 March 26, 2014 March 25, 2014 March 24, 2014 March 23, 2014 Skip Ad × Scenes from Crimea View Photos On Sunday, Russia’s defense ministry said the Russian flag was now flying over 189 military facilities in Crimea. Caption Signs of Russia’s annexation of Crimea continue to take hold in the former Ukrainian peninsula. March 31, 2014 Russian Prime Minister Dmitry Medvedev, center, reviews troops during a wreath-laying ceremony at the World War II memorial in Sevastopol during his visit to Crimea on Monday. Medvedev, who led a delegation of Cabinet ministers on a surprise visit, pledged that Russia will boost salaries and pensions there and pour in resources to improve education, health care and local infrastructure. Alexander Astafyev/RIA-Novosti via Associated Press Buy Photo Wait 1 second to continue.

Many public figures avoided criticizing the military Tuesday, despite the humiliating loss of Crimea and the widely held perception that Ukrainian troops in that region were left uncertain about whether they should stay at their besieged bases or leave for the mainland.

“The army was left to the mercy of fate,” said Vitali Klitschko, the head of the Udar party, edging toward criticism when he said the government needed to become more effective.

“We are at war, and we need someone decisive who can act quickly in extreme situations,” said Yuriy Derevyanko, an independent member of parliament. “We felt there had to be a change, but it’s better not to criticize in times like this. Everyone has to be united.”

The parliament was elected in fall 2012, in a vote considered flawed, favoring then-President Viktor Yanukovych’s Party of Regions.

“We don’t feel we have the nation’s support,” Derevyanko said. “And we have little time.”

Until Feb. 27, Parubiy was a revolutionary — a member of parliament and the Batkivshchyna party who joined the demonstrations against Yanukovych on the Maidan, as Kiev’s Independence Square is known. Parubiy organized the groups defending the square. He took office the same day that Russian-backed gunmen captured the parliament building in the Crimean capital, Simferopol. A hastily arranged referendum in the region March 16, supported by Russian propaganda and troops, resulted in Putin’s annexation of Crimea.

“When we came here,” Parubiy said, “the army was completely destroyed. We didn’t even have fuel to move troops. And our security situation remains very serious, although week by week we are able to control it more.”

Moscow had prepared an operation code-named Russian Spring, he said, mobilizing agents in southeastern Ukraine to stir up disorder, take over government buildings and then appeal to Russia for help, much as it did in Crimea. Russia has moved 100,000 well-equipped and trained troops to the Ukrainian border, he said.

“We have to be ready for anything,” Parubiy said.

Kiev has in recent days deployed more troops and police, tightening up the border and arresting provocateurs, he said. In the eastern cities of Donetsk and Kharkiv, he sad, disorderly crowds have diminished and security has improved.

Another strain on the government emerged Tuesday, at the Interior Ministry, where officials issued a warning to groups that took up arms during the anti-Yanukovych demonstrations to turn them in, or else.

“The time for disarmament is over,” First Deputy Interior Minister Volodymyr Yevdokymov said, directing his comments to Right Sector, a right-wing group, among others. He promised “tough and resolute” measures against those who keep illegal weapons.

Earlier Tuesday, a Right Sector leader died in a confrontation with police in Rivne, in western Ukraine. The circumstances remained unclear, but the man, Oleksandr Muzychko, known as Sashko Biliy, had been involved in several violent incidents recently, attacking a local prosecutor at a public meeting while clutching an automatic weapon.

Russia had declared him wanted March 7, accusing him of torturing and killing Russian soldiers in Chechnya nearly 20 years ago.

Yevdokymov said Muzychko died from a shot from his own pistol as police scuffled with him, trying to arrest him on suspicion of criminal activity. The head of Right Sector, Dmytro Yarosh, demanded the dismissal of the interior minister and the head of the Sokil special police unit involved. He called Muzychko a “brother in arms” who had been murdered.

Back on the Maidan, some protestors remain, determined to keep a watchful eye on the new government. Volodymyr Parasyuk, a 26-year-old who became a hero of the Maidan when he roused the crowd to reject a deal with Yanukovych, said the government was operating as if it was trying to burn a pile of wet debris — sparks were not flying. The defense minister needed to go, Parasyuk said.

“It was a mistake to choose him,” he said. “And there’s no room for mistakes.”

Parubiy, who was injured three times on the Maidan, said governing is turning out to be much harder than revolution.

“I thought the Maidan was tough,” he said. “This is bigger. Much, much bigger. We’re on the barricades.”