http://www.ft.com/cms/s/289ed728-bd26-11db-b5bd-0000779e2340.html Russia threatened on Thursday to pull out of a landmark nuclear arms control treaty unless the US backed away from plans to install its missile defence shield in Eastern Europe. Yury Baluyevsky, the Russian army chief of staff, said Moscow might unilaterally withdraw from the 1987 Intermediate-range Nuclear Forces treaty, which forced the US and the Soviet Union to ban nuclear and conventional ground-launched ballistic and cruise missiles with ranges of 500 to 5,500km. There was â€śconvincing evidenceâ€ť for leaving the agreement because â€śmany countries are developing and perfecting medium-range rocketsâ€ť, he said. But the general also explicitly linked Russiaâ€™s stance to the USâ€™s plans to extend its missile defence into central Europe. The Pentagon is preparing to start negotiations with Poland and the Czech Republic about hosting missile interceptors and radars. Jaroslaw Kaczynski, Polish prime minister, on Thursday expressed conditional support for participating in the system.