By Federico Maccioni and Gianluca Semeraro MILAN (Reuters) -Leonardo’s U.S.-based electronics unit, DRS, has agreed to buy Israel’s RADA Electronic Industries, the Italian defence group said on Tuesday, paving the way for the combined business to list on the Nasdaq stock exchange. Shares in Leonardo rose as much as 9.7% on the news, making it the top performer in Milan’s blue-chip index. Under the agreement, DRS will acquire 100% of the Israeli maker of tactical radar equipment, with current RADA shareholders then taking a 19.5% stake in the combined business. The all-stock takeover comes at a…