* U.S. retail sales post biggest gain in 1-1/2 years
* Ukraine's acting president threatens military action
* Futures up: Dow 69 pts, S&P 10 pts, Nasdaq 20 pts (Updates prices, adds retail sales data, byline)
By Rodrigo Campos
NEW YORK, April 14 (Reuters) - U.S. stocks were set to open higher on Monday, following a sharp selloff last session, with earnings results from Citigroup and retail sales data lifting sentiment while traders kept tabs on the possible escalation of hostilities in Ukraine.
* Equity futures took off after Citi said its quarterly net profit rose as a smaller loss on its troubled assets made up for a drop in revenue and profit from its core trading and lending businesses. Citi shares added 3.7 percent in premarket trading.
* Futures added to gains after data showed U.S. retail sales recorded their largest gain in 1-1/2 years in March, in the latest sign the economy was emerging from its weather-induced slumber and on track to accelerate in the second quarter.
* Ukraine's acting president threatened military action on Monday, after pro-Russian separatists occupying government buildings in eastern cities ignored an ultimatum to leave and another group attacked a police headquarters.
* Russian stocks fell 1.4 percent and the rouble hit its weakest in three weeks as Ukraine's preparedness to fight heightened fears of Russian military intervention and more western sanctions against Moscow.
* S&P 500 e-mini futures rose 10 points, while fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract, pointed to a slightly higher open. Dow Jones industrial average futures were up 69 points and Nasdaq 100 futures rose 20 points.
* On Friday, JPMorgan's disappointing earnings were partly to blame for the day's selloff. Biotech and other momentum stocks led the Nasdaq Composite lower, pushing the index below 4,000 for the first time in two months. A biotech index closed Friday 21 percent below its record closing high hit Feb. 25, entering bear market territory.
* Medtronic shares fell 5.4 percent in premarket trading after a court ruling that would prevent the company from selling its CoreValve system in the United States because of a patent infringement. Shares of Edwards Lifesciences, on the other side of the ruling, rallied 11.7 percent.
* Lexicon Pharmaceuticals rallied 17 percent premarket after it said its experimental drug to treat diabetes met a main goal in a mid-stage study on patients with type 1 diabetes.
* Shares of Aspen Insurance Holdings jumped 20 percent in premarket trading after Endurance Specialty offered to buy Aspen for $3.2 billion in cash and stock. (Reporting by Rodrigo Campos; Editing by Chizu Nomiyama)