The Russian military deployed additional S-400 surface-to-air missile batteries in Crimea after seizing Ukrainian ships last week, according to satellite images obtained by Fox News on Monday.

An intelligence report by ImageSat International appears to show how Russia prepared the infrastructure for the S-400 battery over recent months, well before last weekend’s naval encounters amid talk of a possible Russian invasion.

Images captured in April 2018 show an empty site, while others taken in early November show construction of eight S-400 batteries as well as two radar systems and several large trucks. Experts believe one of those trucks carried the missiles.

The S-400 battery is one of the world’s most powerful anti-aircraft weapon systems, with a range of up to 250 miles and a maximum altitude of almost 19 miles. It is intended to take down any kind of aerial threat, from aircraft to cruise and ballistic missiles.

Russia seized three Ukrainian naval vessels off the Crimean Peninsula last week, accusing them of illegally entering its waters, more than four years after Moscow illegally annexed the region. Last week, Ukrainian President Petro Poroshenko warned the tense situation could escalate into a war of tanks and bombs.

“What happened on November 25th is an extraordinary event that took place for the first time in 4.5 years of Russian aggression,” Poroshenko said in a television interview.” Officially, without tearing off chevrons, without ‘green men,’ Russian troops in large numbers attacked the ships of the Armed Forces of Ukraine.”

“I don’t want anybody to think that it’s a trifle,” he continued. “The country is under the threat of a full-scale war with the Russian Federation.”

Russian leader Vladimir Putin has attempted to downplay the incident, describing it as a “nothing more” than a border incident. He also accused Poroshenko of using the incident to boost his popularity ahead of next year’s presidential election, citing Ukranian authorities declaring a state of martial law.

“This is certainly a provocation organized by the current government, I think, including the current president, on the eve of presidential elections in Ukraine in March next year,” Putin said. “The current president is about fifth in [presidential] ratings, and there is a chance he won’t make it to the second round, so he needs to do something to aggravate the situation and create insurmountable obstacles for his competitors, first of all, from the opposition.”

“Military vessels intruded into Russian territorial waters and did not answer. What were they supposed to do? They would do the same in your country, this is absolutely obvious,” he continued. “These territorial waters were always ours, even before Crimea joined Russia.”

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