Can treason be charged if no war has been declared?

Yes, treason can be charged even if no war has been declared. In the United States, treason is defined in the Constitution as levying war against the country or adhering to its enemies, giving them aid and comfort. This means that acts perceived as betraying the nation can be prosecuted regardless of whether there is an official state of war, as long as the actions meet the legal definitions outlined in the law.