In Syria Russian Su-34s were recently spotted carrying the Kh-35 anti-ship missile. This weapon entered service in 2003 and is similar to the American Harpoon but lighter (520 kg/1,150 pounds, compared to 728 kg) and has less range (130 kilometers compared to 224 for the latest version of Harpoon). The Kh-35 (also known as the SS-N-25 or Switchblade) can also be fired from helicopters, aircraft or shore batteries. The Kh-35 has not been used in combat until now. Like Harpoon Kh-35 can be used against land targets but it is a very expensive weapon for that, costing more than ten times as much as a smart (satellite guided) bomb.
The problem is that Russia never stockpiled a lot of smart bombs and few pilots had much, if any, experience using them. In Syria Russia quickly exhausted its supply of smart bombs, Since the 1990s the United States has increasingly used smart (laser or GPS) guided bombs and now over 99 percent of American air strikes use such weapons. Other Western nations also adopted smart bombs. Russia is known to have had such weapons since the 1970s, many of them based on American smart bombs (or fragments) captured in Vietnam.
The problem was that Russia never built or used a lot of these weapons. For a long time Russia considered these special weapons to be used only for rare situations. The demands of Syria have been such that by the end of 2015, after about two months of Russian warplanes bombing targets in Syria, there were very few Russian smart bombs left and new production was not ample enough to change the situation much. So in 2016 there are increasing reports of Russian warplanes coming in low to deliver dumb (unguided) bombs. This makes the Russian warplanes more vulnerable to ground fire but none have been shot down yet. Some have probably been damaged but the larger problem is the lack of smart bombs. So seeing the Kh-35 in use against ground targets makes sense.
The 45 ton Su-34 is yet another variant of the 33 ton Su-27, and is very similar to the 36 ton U.S. F-15E (a two seat fighter bomber version of the 31 ton F-15C). The Su-34 can carry over ten tons of weapons, including nearly all the air-to-air and air-to-surface missiles Russia makes as well as all Russian guided bombs.