S-400 Triumf surface-to-air missile launchers are seen during the Victory Day military parade in Moscow, Russia on May 09, 2018.

WASHINGTON — The Russian S-400 missile system costs a fraction of rival platforms made by U.S. companies, one of the major reasons several countries are interested in dealing with the Kremlin despite the potential for blowback.

Russia's S-400, a mobile long-range surface-to-air missile system, costs approximately $500 million, whereas a Patriot Pac-2 battery costs $1 billion and a THAAD battery rings in at about $3 billion, according to people with first-hand knowledge of a U.S. intelligence assessment.

Lockheed Martin makes the THAAD, or terminal high altitude area defense, system, while Raytheon makes the Patriot system.

Nearly 13 countries have expressed interest in buying Russia's S-400, a move that could trigger potential U.S. sanctions under the Countering America's Adversaries Through Sanctions Act, which President Donald Trump signed in August 2017. In September, the U.S. slapped sanctions on China for buying fighter jets and missiles from Russia. However, the U.S. could grant sanction waivers.

Russian arms are generally considered less expensive than American weapons, in large part because they come without extensive maintenance support.

"When foreign militaries buy American, above and beyond the purchase, they are buying a partnership with the U.S. military," Andrew Hunter, director of the Defense-Industrial Initiatives Group at the Center for Strategic and International Studies, told CNBC. "And that plus the maintenance and technical assistance is a big part of the cost difference."

The Pentagon did not immediately respond to a request for comment for this article.

The S-400 system, the successor to the S-200 and S-300 missile systems, made its debut on the world stage in 2007. Compared with U.S. systems, the Russian-made S-400 is capable of engaging a wider array of targets, at longer ranges and against multiple threats simultaneously.

In terms of capability, one source noted that while there is no perfect weapon, the S-400 eclipses even THAAD, America's missile defense crown jewel.

When asked why nations seek to buy the S-400 instead of America's Patriot or THAAD systems, one of the people with knowledge of the intelligence report explained that foreign militaries aren't willing to stick with the cumbersome process of buying weapons from the U.S. government.

"Many of these countries do not want to wait for U.S. regulatory hurdles," said a source with first-hand knowledge of the assessment. "The S-400 has less export restrictions and the Kremlin is willing to expedite sales by skipping over any regulatory hurdles."

China, India and Turkey have already signed purchase agreements with the Kremlin.

China, which is embroiled in a trade battle with the U.S., is in the middle of receiving its final shipment of the S-400 system. India, the top buyer of Russian arms, signed a deal with Moscow for the S-400 last month. Turkey, a NATO ally, is slated to receive its S-400 next year and is expected to have the system ready for use by 2020.

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