A blockade is an act of war...
It is not a blockade. A blockade is an international act of war wherein one state blockades the ports of an enemy state. A state cannot blockade itself. Lithuania is not blockading all the ports of Kaliningrad, much less Russia.
There are several candidate terms for what has been done, from least plausible to most plausible:
In a blockade, as instituted in the American Civil War, all nations of the world are informed of its existence and are prohibited from running the blockade. Any ship detected running the blockade may be pursued and captured on the high seas. A blockade only happens at an enemy's coast.
The domestic act is a closing of the ports. That is where a nation prohibits ships entering or leaving its own ports. Near the end of the war, on April 11, 1865, Lincoln proclaimed a change from blockade to a closing of the ports.
An embargo is an economic policy to not trade with another state. An example would be the United States embargo against Cuba. All trade is prohibited.
A sanction is rather like a selective, limited or targeted embargo. It does not suspend all trade. The action by Lithuania is a sanction, an economic coercive measure taken against another state to force it to comply with international law.
https://en.wikipedia.org/wiki/Blockade
A blockade is the act of actively preventing a country or region from receiving or sending out food, supplies, weapons, or communications, and sometimes people, by military force. A blockade differs from an embargo or sanction, which are legal barriers to trade rather than physical barriers. It is also distinct from a siege in that a blockade is usually directed at an entire country or region, rather than a fortress or city and the objective may not always be to conquer the area.
https://www.mei.edu/publications/blockade-and-embargo-have-different-meanings
MIddle East InstituteAn embargo is when one nation establishes a policy not to trade with another nation and not to allow its own ports or territory to be used for commerce with that nation. Establishment of an embargo is the prerogative of any nation. For decades the United States has had an embargo on trade with Cuba. This is a policy decision which has been made by the Government. The policy may be wise or foolish, but nations are clearly within their rights to establish embargos.
Similarly, Israel and Egypt have a right to embargo trade with Gaza. If Egypt or Israel believes the Government in Gaza poses a threat to its stability or security, they have a right to place an embargo on Gaza. What that means is that trade with Gaza is restricted through Israeli and Egyptian ports and territory. Nations have the right to secure their borders and the Israelis and the Egyptians are exercising that right.
A blockade is totally different. A blockade is closing to international commerce by military force the coast of another entity. A blockade prevents third parties from undertaking normal commercial activity. A blockade is an act of war rather than merely exercising one’s own prerogatives.
In 1967, when the Government of Egypt closed the straits of Tiran to Israeli or third party commerce with the port of Eilat, they established a blockade. The Egyptians, thus, initiated a war with Israel. The Israelis were, therefore, justified in launching their military operations against Egypt in June 1967. The Egyptian blockade of the straits differed significantly from the Arab League policy of boycotting Israel. Blockading the straits crossed the line from a confrontational policy to an act of war.
In legalese:
Black's Law Dictionary, 11th Ed.
blockade, n. (17c) Int’l law.A belligerent’s prevention of access to or egress from an enemy’s ports by stationing ships to intercept vessels trying to enter or leave those ports. • To be binding, a blockade must be effective — that is, it must be maintained by a force sufficient to prevent access to ports. — Also termed simple blockade; de facto blockade.
“A blockade must be existing in point of fact; and in order to constitute that existence, there must be a power present to enforce it. All decrees and orders, declaring extensive coasts and whole countries in a state of blockade, without the presence of an adequate naval force to support it, are manifestly illegal and void, and have no sanction in public law.” 1 James Kent, Commentaries on American Law *144 (George Comstock ed., 11th ed. 1866).
“The word blockade properly denotes obstructing the passage into or from a place on either element, but is more especially applied to naval forces preventing communication by water. Unlike siege it implies no intention to get possession of the blockaded place. With blockades by land or ordinary sieges neutrals have usually little to do.” Theodore D. Woolsey, Introduction to the Study of International Law § 202, at 351 (5th ed. 1878).
“The term ‘blockade’ is all too often used for measures that do not qualify as a blockade proper, such as sieges on land or the barring of passage through an international strait or an international canal. Sometimes the use of the term is cautiously avoided because states are unwilling to admit that they are indeed establishing and enforcing a blockade against another state. Neither the erroneous use of the term nor the refusal of its use [is] relevant to the legal concept of blockade. A blockade is a military operation to prevent all vessels and/or aircraft from entering or exiting specified ports, airports, or coastal areas belonging to or under the control of another state. Hence, a blockade by its very nature can only be established off the coast of another state and not within the territory of another state or within a sea area that is not geographically connected with land territory, that is, on the high seas.” Wolff Heintschel von Heinegg, “Blockades and Interdictions,” in The Oxford Handbook of the Use of Force in International Law 925, 927 (Marc Weller ed., 2015).
• pacific blockade. (1887) Int’l law. A blockade that is established without a declaration of war.
• public blockade. (1865) Int’l law. An established blockade of which the blockading country gives formal notice to the governments of neutral countries.
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embargo3. The unilateral or collective restrictions on the import or export of goods, materials, capital, or services into or from a secific country or group of countries for political or security reasons —Also termed trade embargo, economic-cure trade embargo.
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4. Int'l law An economic or military coercive measure taken by one or more countries toward another to force it to comply with international law. . sanction
You must not be a lawyer, because the definitions you posted prove that your conception of a what a blockade must be is totally wrong.