US STOCKS-Futures imply modest gains, Wall St on track for strong week
* Major indexes on track for strong weekly gains
* U.S. and Russia engage in tit-for-tat sanctions
* Nike shares fall in premarket after outlook
* Futures up: Dow 20 pts, S&P 4.2 pts, Nasdaq 9.5 pts (Updates prices and adds Media General deal)
By Ryan Vlastelica
NEW YORK, March 21 (Reuters) - U.S. stock index futures pointed to a slightly higher open on Friday, with major indexes on track for a week of strong gains, though geopolitical concerns remained in view as the tenuous situation in Ukraine continued.
* The biggest East-West confrontation since the Cold War ramped up after U.S. President Barack Obama targeted some of Russian President Vladimir Putin's closest long-time political and business allies in response to Russia's seizure of Crimea from Ukraine. Russia retaliated with sanctions of its own against top U.S. politicians.
* With the S&P 500 within 1 percent of record levels, some analysts say equities are vulnerable to any fallout from escalating geopolitical tensions, even though few U.S. companies have substantial exposure to the region. Still, stocks have moved sharply higher this week, boosted by Moscow's assertion that no other Ukrainian region would be subject to intervention.
* In another facet of emerging market concerns, Nike Inc late Thursday said growing pressures from weaker emerging market currencies would take a big toll on its profit in the current quarter. The athletic apparel maker, which gets about 30 percent of its revenue from emerging markets, also said China sales would be unchanged or slightly down this quarter. Shares fell 3.5 percent to $76.50 in premarket trading. Continuación...