THE Russians seem to have gone more than half way towards showing their keenness to mend relations with the Americans. An agreement, which President Dmitry Medvedev signed with visiting President Barack Obama in Moscow on Monday permitting the transit of US troops and weapons to Afghanistan, would considerably reduce Pentagon's dependence on Pakistan for the passage of arms and ammunition and its worry about their safety. Militants have blown up trucks on several occasions when they were transiting through Pakistan to Afghanistan. No doubt, Moscow is as much as concerned about terrorism as Washington but this gesture of allowing its air space for 4,500 flights a year would prove of great help to the US actually engaged in the fight against militants. One would like to hope that the agreement (subject to ratification by the Russian parliament) to cut the number of nuclear warheads in the arsenals of each country to between 1,500 and 1,675 within seven years would ultimately pave the way for a complete global nuclear disarmament. Short of that would be to miss the threatening outcome that would find some nations striving to possess the deadly weapon by hook or by crook. Some time back, Mr Obama referred to his vision of a nuclear-free world, and even though the journey is arduous, the importance of this agreement that might turn out to be the first step towards the goal cannot be downgraded. Yet, the improvement of US-Russia relations is dogged by differences on crucial issues. The persistent effort to extend the NATO domain to the border of Russia, the plan for a missile defence shield in Poland and Czech Republic and the Russian intervention in Georgia are real irritants. There is need for the leaders in the two countries to demonstrate sincerity in recognising each other's concerns and work together to remove them so that issues like nuclear disarmament, which would serve the cause of the entire humanity, could be tackled with full attention.