LONDON (Reuters) -President Vladimir Putin completed the formal annexation of more than 15% of Ukraine on Wednesday just as Russian forces battled to halt a Ukrainian counter-offensive across swathes of the territories. In the biggest expansion of Russian territory in at least half a century, Putin signed laws admitting the Donetsk People’s Republic (DPR), the Luhansk People’s Republic (LNR), Kherson region and Zaporizhzhia region into Russia. “Russian President Vladimir Putin has signed four federal constitutional laws on the entry of the Donetsk and Lugansk People’s Republics, Zaporozhye and…