Washington. The United States has deployed two nuclear-capable stealth bombers over South Korea as part of a "deterrence” mission over the Korean peninsula. The deployment of B-2 bombers yesterday followed North Korea’s decision to cut a military hotline with the South, breaking the last direct communication link between the two countries at a time of heightened military tensions.The bombers made the 20,000km round trip from the US state of Missouri to South Korea in a single flight. Clear message to North KoreaThe US Defence Secretary Charles Hagel has called his South Korea counterpart "to reaffirm the commitment” of the US to defend its ally.   On Wednesday, the North said it would inform the UN Security Council that the threat of nuclear war in the region is growing."Under the situation where a war may break out any moment, there is no need to keep up North-South military communications,” the official was quoted as saying by the official Korean Central News Agency. "From now, the North-South military communications will be cut off.”In response to the latest provocation, the US said it is ready to respond to "any contingency.”"North Korea’s bellicose rhetoric and the threats that they engage in follow a pattern designed to raise tensions and intimidate others,” Jay Carney, the White House spokesman, said. Several weeks ago North Korea severed the Red Cross hotline that had been used for government-to-government communications in the absence of diplomatic relations.Despite the cutting of the military hotline, the Seoul-funded Kaesong industrial complex in North Korea continued to operate as of yesterday.The industrial estate, established in 2004 as a symbol of cross-border cooperation, has remained operational despite repeated crises in relations.‘Simmering’ warThe North has also threatened war against the South and its ally the US, saying conditions "for a simmering nuclear war” have been created on the peninsula.North Korea had repeated threats to target US military bases. Pyongyang said its military would put all field artillery units, including long-range artillery units and strategic rocket units, into combat duty position that will target all "enemy objects” in the US, "invasionary” bases on its mainland, Hawaii and Guam.The rhetoric from N. Korea drew more concern from China, Pyongyang’s only major ally, which said the situation was ‘sensitive’.South Korea and the US military are conducting military drills until the end of April, which they have stressed are strictly defensive in nature.