Russia could be preparing for a space war, following the launch of three mysterious satellites within 18 months, according to U.S. military analysts.

The three spacecraft - which the Kremlin say are communication satellites - could be prototype weapons, say U.S military observers.

As is standard, Russia notified the United Nations of the launch of three of its Rodnik communication satellites last year, but also added a fourth, unexpected craft to the list.

In contrast to the unpowered Ronik satellites, the mystery vehicle appeared to manoeuvre itself into a different orbit.

Following the launch in May 2014, Russia has launched two more of the baffling spacecraft.

It is feared that the three small unidentified craft - dubbed Kosmos-2491, -2499 and -2504 - could be potentially be used as anti-satellite weapons, largely due to their ability to get extremely close to existing satellites.

Several nations, including the U.S. and China have developed anti-satellite weaponry in the past, but a similar move from Russia could be seen as troubling, given the reliance of space agencies such as NASA on the Russian Soyuz spacecraft.

The Soyuz is currently the only way for astronauts to get to the International Space Station (ISS), which is a joint endeavour between Russia, the U.S., Japan and the European Space Agency.

According to the MailOnline, officials as Russia’s federal space agency insist that the satellites are ‘absolutely peaceful vehicles’.

(Image credit: Wikipedia)