just a year ago, china placed an oil rig off the coast of --tnam, that trickled triggered a diplomaticween the countries. china as well as constructing artificial islands which is upsetting vietnam and other countries. vietnam views this as a threat it'se economy and sovereignty. have one of the largest shipping lanes in the world. you will see more and more engagement. time, both countries are involved in negotiations with the transpacific partnership treaty. so they view the future as being a much more economically engaged. there are limitations to how close, led vietnam and the u.s. can get, aren't there? reporter: serious obstacles remain for this relationship. vietnam is wary of how china considers if it vietnam to be cozying up to the u.s. china is the most important trading partner. the united states still has continued concerns about vietnam human rights record, although that has been integrated -- improving according to the state department. while you want see them becoming iose allies anytime soon, think you will see further engagement, including possible visits to vietnam by