Russian President Dmitry Medvedev warned the United States yesterday that if it did not reach agreement with Russia on plans for missile defence systems, Moscow would deploy rockets in an enclave near Poland.

In sharp contrast to his positive words during President Barack Obama's visit to Moscow earlier this week when the two reached broad agreement on nuclear arms cuts, Mr Medvedev used a news conference at the G8 summit to return to Russia's earlier tough rhetoric on arms control.

Referring to an order he gave earlier this year to prepare deployment of short-range Russian missiles in the western enclave of Kaliningrad to answer to any US deployment of a missile shield in central Europe, Mr Medvedev said:

"If we don't manage to agree on the issues, you know the consequences. What I said during my state of the nation address has not been revoked."

Mr Medvedev also appeared to change his tone on the missile defence shield itself.

During Mr Obama's visit he told the US leader, using markedly softer language than normal, that "no one is saying that missile defence is harmful in itself or that it poses a threat to someone."

But at the Group of Eight rich nations summit in Italy yesterday, Mr Medvedev returned to a traditional posture on the system, describing it as "harmful" and "threatening to Russia."

In Moscow, Mr Medvedev and Mr Obama agreed a target for cuts in nuclear arms and a year-end deadline for a reduction deal. Mr Obama praised Mr Medvedev as a "straightforward professional" leader.

Before his Moscow visit, Mr Obama made clear he would not accept any effort by Moscow to link arms control to missile defence, and reiterated Washington's stance that any system would be to protect against a threat from Iran, not from Russia. He has been less enthusiastic about the plan, which will put a radar installation in the Czech Republic and 10 interceptor missiles in Poland, than predecessor George W. Bush, but seems unlikely to abandon it without getting something in return.

The Czech Republic and Poland have signed treaties with Washington on the plan, with both governments making the project a priority to counter what they see as Russia's continued influence in the region.