yes
A) expressed powers
You can find all the congressional powers, including the dealing with foreign relations, in Article 1 of the US Constitution.
They limited the powers of their government by Separation of Powers. This means that power is divided among 3 branches. The 3 branches are Judicial, Executive and Legislative.
The separation of powers is the practice we use in the US national government to divide the national government's powers between the three branches (executive, legislative, judicial) so that the national government cannot abuse its powers. Each branch has certain powers and is able to "check" the other branches' powers to keep the three branches equal or "balanced". This system is known as the system of checks and balances and it is used to guarantee the separation of powers.
The federal government controls drinking age, foreign affairs, granting citizenship and alien cards, and social security.
Separation Of Powers
The constitutional powers that help to limit the power of government is dividing it into three branches. The three branches of government are executive, legislative and judiciary.
no
No, states cannot declare war or regulate foreign commerce. These powers are reserved for the federal government, specifically the executive branch (president) and Congress. States have limited authority in matters of foreign affairs and international relations, which are primarily handled at the federal level.
"Seperation of Powers" and checks & balances
Separation of powers.