Is the United States in a state of war with Iran?
<p>As of January 7, 2020, Is the US at war with Iran?</p>

<p>What is the litmus test to determine if the US is at war with Iran?</p>

<p>No (assuming that nothing new as happened since I last saw the news earlier today, these matters can change in a matter of hours during the course of a day).</p>
<p>There has been no declaration of war by Congress (which has the sole power to declare war under the U.S. Constitution), there has been no authorization by Congress to use military force (the modern functional equivalent of a declaration of war), and Iran has not taken acts which by definition constitute an act of war that have been used to treat the two countries as at war (such as conducting prolonged mutual battles between military forces, as opposed to a single attack).</p>
<blockquote>
<p>War does not exist merely because of an armed attack by the military
forces of another nation until it is a condition recognized or
accepted by political authority of government which is attacked,
either through an actual declaration of war or other acts
demonstrating such position.</p>
</blockquote>
<p>-- Blacks Law Dictionary, &quot;War&quot; (5th Ed. 1979) (<em>citing</em> <a href="https://law.justia.com/cases/federal/district-courts/FSupp/57/620/2399474/" rel="nofollow noreferrer"><em>Savage v. Sun Life Assur. Co. of Canada</em></a>, 57 F. Supp. 620, 621 (W.D. La. 1944)).</p>
<p>Thus, the fact that Iran appears to have fire missiles at U.S. targets, in and of itself (which the New York Times <a href="https://www.nytimes.com/2020/01/07/world/middleeast/trump-iran.html?action=click&amp;module=Top%20Stories&amp;pgtype=Homepage" rel="nofollow noreferrer">indicates</a> as of 9:34 EST that it has) does not cause the U.S. and Iran to be at war. This story states that:</p>
<blockquote>
<p>The Asad and Erbil bases were targeted by Iran in retaliation for the
killing of a top Revolutionary Guards commander in Baghdad.</p>
<p>American military officials said that Iran had launched more than a
dozen ballistic missiles against United States military and coalition
forces.</p>
</blockquote>
<p>I am not aware at this moment, however, of any official reaction or statement regarding how this action will be classified by the United States, although that could happen very quickly before the day is out even.</p>
<p>What matters in determining whether or not the U.S. and Iran are &quot;at war&quot; is the meaning that is assigned to this attack by the President, cabinet members and senior military and diplomatic officials, and Congress.</p>
<p>Notably, being &quot;at war&quot; with a country does not mean, by definition, that the other country is &quot;at war&quot; with you. One country often becomes &quot;at war&quot; with another country at a different time that the second country comes to be at war with the first country. So, even if Iran's Parliament had declared war on the U.S, that wouldn't necessarily automatically and immediately cause the U.S. to be &quot;at war&quot; with Iran for purposes of U.S. law, even though a declaration of war in response would usually follow in short order.</p>
<p>@user6726 however, accurately and importantly notes that the isn't a single universal definition of &quot;being at war&quot; with a country that applies for all purposes. The correct definition depends upon the context and the purpose for which you are asking the question, and the consequences that flow from a determination that we are &quot;at war&quot;.</p>
<p>N.B. One of the important reasons to know if you are &quot;at war&quot; or not, among others, is that an &quot;enemy&quot; for legal purposes, generally only includes someone you are at war with. Citizens or nationals of a nation with whom you are at war are &quot;enemies&quot; and have different legal rights that citizens or nationals of foreign countries with whom you are not at war.</p>

<p>Congress has not officially declared war since WWII. We have "been at war" <a href="https://en.wikipedia.org/wiki/Declaration_of_war_by_the_United_States#Formal" rel="nofollow noreferrer">a number of times</a>. There is a <a href="https://fas.org/sgp/crs/natsec/RL31133.pdf" rel="nofollow noreferrer">long legal analysis</a> which exposes the nuances of the question, for example (start p. 49) 
<a href="https://www.law.cornell.edu/uscode/text/2/198" rel="nofollow noreferrer">2 USC 198(b)</a> says that the adjournment statute is not applicable in case of declared war:</p>

<blockquote>
  <p>This section shall not be applicable in any year if on July 31 of such
  year a state of war exists pursuant to a declaration of war by the
  Congress.</p>
</blockquote>

<p>Since there is no declared state of war, Congress can adjourn. It really depends on what legal fact you are asking about. 10 USC 12521 addresses "a  period  of  war  declared  by  Congress  or  a  period  of  national emergency declared by the President or Congress" – as it happens, there are 11 current states of emergency in the US, most from the Obama administration. It just depends on what the relevant statute says.</p>

laws-of-war