Vladimir Putin has said he was "ready" to place Russia's nuclear forces on alert as he sought to annex the Crimean peninsula last year.
Speaking during a documentary aired on Russian state TV, the Russian President said he was prepared to face "the worst possible turn of events" in the Crimea.
The documentary, titled Homeward Bound, was aired to mark a year since the takeover of the Black Sea peninsula from Ukraine.
It featured interviews with Mr Putin and a reconstruction of events which presents the Russian leader as the saviour of Crimea.
Asked whether he was ready to put Russia's nuclear forces on alert, Mr Putin said: "We were ready to do this."
He said during negotiations with foreign leaders he explained that "this (Crimea) is our historical territory and Russian people live there... and we cannot abandon them".
"It was a frank and open position. And that is why I think no one was in the mood to start a world war," he added.
The annexation of the Crimean peninsula was seen by the West as an illegal occupation.
Mr Putin said in the documentary that after Ukrainian leader Viktor Yanukovych fled Kiev in the face of a pro-Western revolution, he organised a secret poll to test the opinions of the Crimean population.
"But it was not us who carried out the coup d'etat," Mr Putin said.
"This was done by nationalists and people with extreme beliefs."
With support for absorption into Russia high, he sent in thousands of Russian special forces, marines and airborne troops to neutralise the Ukrainian military.
"In order to block and disarm 20,000 well-armed men, you need a specific set of personnel. We needed specialists who know how to do it," Mr Putin said.
Russia's annexation of Crimea was a critical event in the Ukrainian crisis.
The move plunged Moscow's relations with the West to lows not seen since the Cold War.
It also played a role in triggering the separatist uprising in eastern Ukraine, where more than 6,000 people have since died in fighting.