- Summary- NATO warns against attack on its members' infrastructure- G7 reviews Kyiv's request for air defence systems- May also warn Belarus against closer involvement- Russia says it will respond to greater Western aidKYIV, Oct 11 (Reuters) - U.S.-led NATO said on Tuesday its member states were boosting security around key installations as Russia escalated its attacks on Ukraine and stepped up threats against the West.Russian President Vladimir Putin, under domestic pressure to ramp up the seven-month war as his forces have lost ground since early September, said he had ordered the strikes as revenge for a blast that damaged Russia's bridge to annexed Crimea.The White House said U.S. President Joe Biden and other G7 leaders met virtually on Tuesday to discuss what more they could do to support Ukraine and they listened to President Volodymyr Zelenskiy, who has called air defence systems his "number 1 priority".Biden has already promised more air defences, a pledge that Kremlin spokesman Dmitry Peskov said would extend the conflict."We warn and hope that they realise the danger of uncontrolled escalation in Washington and other Western capitals," Russian Deputy Foreign Minister Sergei Ryabkov was quoted as saying by RIA news agency on Tuesday."