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Western leaders have agreed to strengthen their forces in Eastern Europe and impose fresh sanctions as the Russian assault on Ukraine enters its second month.
On a busy day of diplomacy in Brussels, a NATO emergency summit also pledged more military aid to Ukraine, including the means to help the country against biological, chemical and nuclear attacks - as well as cyber warfare.
Retired British military officer and chemical weapons expert Hamish de Bretton-Gordon spoke to Guyon Espiner from the UK.