The BBC's Tom Carver reports on the talks

The system breaches the Anti-Ballistic Missile Treaty signed with Moscow in 1972 and Washington now wants an agreement with Russia to amend the pact.

Officials from both countries were due to start talks in Moscow on Tuesday. The consultations will also raise the issue of a Start III treaty that could cut arsenals to 2,000 warheads for Russia and 2,500 for the US.

The Pentagon intends to spend $1bn a year researching a weapon that would be capable of protecting mainland America.

Ronald Reagan: First proposed 'Star Wars'

The plan is to set up 100 interceptor missiles around the country which would be fired at incoming hostile rockets - a system remeniscent of the one proposed by former US President Ronald Reagan.

It retains some of the features of the so-called Star Wars project which was abandoned because it was seen as too costly and too complex to develop.

The decision to resume development work on a national missile defence system has irked Russia because it is a breach of the 1972 treaty. The pact prohibits Russia and America from building a national defence system.

Rogue nations

US officials argue that with the end of the Cold War, this system would not be directed at Russia but at nations perceived as a threat, such as North Korea. The reclusive communist state caught world leaders unawares last August when it test-fired a ballistic missile across Japan.

In March, the US House of Representatives approved a statement making it national policy to put in place a system to defend against incoming missiles.

Demanding concessions

The Senate had previously voted to commit the government to the deployment of a missile defence shield as soon as technology permitted.

It was reported at the time that congressional approval for the project had increased as a reaction to efforts by North Korea and Iran to develop long-range missiles.

The US is now asking Russia to agree to amend the treaty to allow the defence system to be built. But our correspondent in Washington, Tom Carver, says it is unlikely Russia will agree to change the treaty without being given some concession.

He says Russia will most likely ask the US to unilaterally disarm parts of its nuclear arsenal, but this is something the latter has resisted.

Intercept and destroy

The US has not yet designed the interceptors but it has already developed and tested a smaller system capable of defending a country the size of Israel.

In June, the US tested the Theatre High Altitude Area Defence missile, or Thaad. According to Pentagon officials, the missile intercepted and destroyed its target high over New Mexico.

Almost $4bn has been spent on the development of Thaad since 1992.

This week Japan and the US agreed a joint research project on a new regional anti-missile defence system.

Tokyo and Washington agreed on the $500m project, partly in response to what they perceive as a threat from North Korea.