The United States of America has just awarded its most expensive shipbuilding contract on Monday. Several sources have estimated that the U.S. government will spend more than $22.2 billion worth of advanced nuclear-powered submarines.

The deal comes after the U.S. Navy warned of a massive Chinese naval build-up in the Pacific, CNN reported. It is the U.S.' response to rising military might of the Asian super power and its aggressive actions in the South China Sea region.

Carl Schuster, a former director of operations at the U.S. Pacific Command's Joint Intelligence Center, said that the "Chinese Navy is getting better and larger." The $22.2 billion deal aims to counter that intimidation, "the U.S. Navy has to respond," according to Schuster.

The Virginia class subs are the U.S. Navy's essential multi-mission undersea program. The nuclear-powered craft are capable of engaging other submarines and can also attack ships and land targets.

If North Korea is capable of launching missiles from submarines -- something analysts say it is on its way to achieving -- that would give it a second strike capability
If North Korea is capable of launching missiles from submarines -- something analysts say it is on its way to achieving -- that would give it a second strike capability KCNA VIA KNS / KCNA VIA KNS

The subs are also able to conduct specialized missions, including intelligence gathering and surveillance. Eighteen Virginia class subs are already in the U.S. Navy's fleet, with another 10 under construction.

However, the nine new subs will be a substantial upgrade over their predecessors, making them more efficient and deadlier in terms of firepower. The U.S. Navy also has an option to build a 10th submarine in the contract, bringing the total contract value close to $24 billion.

Rear Adm. David Goggins, the Navy's program executive officer for submarines, said the new units would bring "a generational leap in submarine capability." The new Virginia class subs will be bigger, 10,200 tons, compared to 7,800 for the current subs, and longer at 460 feet compared to their predecessors' 377-foot length.

They will also feature a substantial upgrade for munitions, with the ability to launch 40 Tomahawk cruise missiles compared to 12 on current units. The new subs can also generate their own water and oxygen supply and can stay submerged for months at a time.

Thomas B. Modly, the acting Secretary of the U.S. Navy, said the "submarine force is fundamental to the power and reach of our integrated naval force." He added that the announcement "affirms our commitment to the future strength of our nation... and around the world."

General Dynamics Electric Boat, based in Groton, Connecticut, will be making the state-of-the-art subs in partnership with the Huntington Ingallls Industries as subcontractors. U.S. Sen. Jack Reed hailed the contract, saying it will ensure stable employment for the 4,000 workers at the Electric Boat shipyard in Rhode Island for many years.

Senator Reed added that "these next-generation submarines provide our forces with a distinct national security advantage. The new Virginia class subs are scheduled for delivery between 2025 and 2029.

China's Navy is expected to field 65 to 70 submarines by 2020, according to the U.S. Defense Department. Experts agree that the U.S. is facing unprecedented pressure in the Pacific due to China's economic growth and rapid militarization.

Beijing's military power is expected to grow even more. Global think-tanks believe that in the next five years, China will begin to manufacture more nuclear-powered attack submarines comparable to the U.S. Virginia class boats.