Rishi Sunak has touched down in the Latvian capital, where he is meeting northern European allies to discuss countering Russian aggression.The Prime Minister landed in snowy Riga at 11.20 am local time, stepping out of the plane into a gusty -4C.He will urge fellow leaders of the Joint Expeditionary Force to stand firm in their support for Ukraine, after announcing a major new artillery package for the war-torn nation.He will continue his whistlestop tour by flying to Estonia later on Monday, where he will meet British troops and sign a new technology partnership.