By Karin Strohecker LONDON (Reuters) -Russia retaliated in what it has called an “economic war” with the West on Tuesday by offering to buy back its $2 billion Eurobonds maturing next month in roubles rather than dollars. The finance ministry offer on Eurobonds maturing on April 4, Russia’s biggest debt payment this year, follows Western moves to tighten sanctions against the country over its invasion of Ukraine and to freeze Moscow out of international finance. Moscow, which calls its actions in Ukraine a “special military operation”, says Western measures amount to “economic war”. In respons…