( LEAD ) U . S . senators urge Trump to use summit with Xi to end Beijing ' s retaliation against S . Korea over THAAD ( ATTN : ADDS S . Korea ' s response in last 2 paras ) WASHINGTON / SEOUL , April 5 ( Yonhap ) -- A bipartisan group of U . S . senators on Tuesday urged President Donald Trump to use his upcoming summit with Chinese President Xi Jinping to bring an end to " unwarranted and unfair " retaliatory measures Beijing has taken against South Korea for hosting the U . S . THAAD missile defense system . A total of 26 senators , led by Dan Sullivan ( R - AK ) and Benjamin Cardin ( D - MD ) , made the appeal in a joint letter to Trump just two days before he is set to host China ' s Xi for high - stakes talks expected to cover all - important security and economic issues , including the North ' s nuclear and missile threats . The Trump - Xi meetings , set for Thursday and Friday at Trump ' s Mar - a - Lago resort in Florida , will also be watched closely as to whether the U . S . stands up to China for bullying South Korea for hosting a THAAD battery , designed to defend against missile threats from North Korea . " While China continues to aggressively oppose a missile defense system on the Korean Peninsula , China has done little in recent years to slow or halt North Korea ' s missile and nuclear programs — the only reason this system is needed , " the senators said in the letter . " Mr . President , we hope you will call upon President Xi to reexamine his view of the THAAD deployment and encourage his country to cease its unwarranted and unfair economic retaliation against South Korea , " they said . They also said China should use its " considerable influence " over Pyongyang for the North ' s denuclearization . " As President Xi knows well , THAAD is a defensive missile system critical to protecting the Korean people and , just as importantly , the tens of thousands of American troops and their families stationed in Northeast Asia from evolving North Korean capabilities , " the senators said . " In your discussions with President Xi , we hope you will underscore that the United States and the Republic of Korea ' s joint decision to deploy THAAD is entirely a result of North Korea ' s continued aggressive behavior , " they said . South Korea ' s foreign ministry viewed the latest U . S . senators ' action toward China ' s retaliation against the THAAD deployment as " very meaningful " in that it came right ahead of the summit and that it directly urged President Trump to send a " clear message " on that issue when he meets the Chinese leader . The ministry added that the Seoul government will continue to prepare diverse countermeasures and take necessary steps in close coordination with the U . S . jschang @ yna . co . kr ( END )