The heads of two U.S. Senate committees overseeing national security have expressed concern to the Obama administration over a recent network supply deal between Chinas Huawei Technologies Co Ltd and Washington ally South Korea. South Korea, which hosts some 28,000 U.S. soldiers to deter potential provocation from North Korea, said Huaweis deal to supply mobile network equipment does raise security concerns, but it has no immediate plan to look into the issue. U.S. Vice President Joe Biden is due to visit Seoul later this week as part of a broader Asia trip.