Secretary Hughes Tells Washington.—(By A. P.)—To maintain its position regarding the Island of Yap, the American government "would have to prove not merely the fact that President Wilson made reservations concerning it, but also that the supreme council decided in favor of those views," the Japanese government says in a note dated last February 26 and made public today by the state department with other correspondence on the subject. Secretary Hughes, in his reply, dated April 5, said that the United States is unable to agree with this contention. He declared: "As no treaty has ever been concluded with the United States relating to Yap, and as no one has ever been authorized to cede or surrender the rights or interest of the United States in that island, the United States is unable to recognize the validity of the Japanese mandate." Central America Plans War—Hughes Issues Ultimatum. WASHINGTON.—(By A. P.)—Guatemala, Honduras and Salvador, members of the Central American union, are pledged to declare war simultaneously with Costa Rica against Panama if Costa Rica deems such action necessary, in view of the present boundary dispute with Panama, according to official advices received here today. United States Will Whip the Whole Bunch WASHINGTON.—(By A. P.)—Resumption of hostilities between Costa Rica and Panama over the White boundary award will not be tolerated by the United States, It was learned officially today. It is understood that both governments have been informed to this effect. No Move For Disarmament. 