He said to his wife: You are divorced when we go back to our country

If the husband said to the wife: You are divorced when we go
back to our country, then the divorce takes effect when you return to your
country, because this is what he meant, i.e., it was not intended to
encourage or discourage, or to confirm or deny, rather it is like when a
person says: “When the first day of the month comes”, or “when Ramadan
comes”, or “when the ruler comes, then my wife is divorced.” By saying these
words, your husband did not intend to prevent you or prevent himself from
returning to his country, nor did he intend to encourage you to stay outside
your country; what he meant was divorce. 

If we assume that he said: “I meant that I would divorce you
after we came back”, this is not acceptable either, because by saying “You
are divorced”, clearly using the word divorce (talaaq), it cannot be
accepted that what he meant and intended was a threat of divorce. 

As for the statement of divorce which is intended to stop
someone doing something, such as saying, “You are divorced if you go out of
the house”, intending to prevent her going out, or that which is intended to
encourage her to do something, such as saying, “You are divorced if you do
not come back to the house,” this is a statement of divorce concerning which
the scholars differed. The majority of them are of the view that divorce
does take place when the thing stipulated happens, but a number of them are
of the view that divorce does not take place, because he did not intend to
divorce her, rather he intended to encourage her to do something or prevent
her from doing something. 

Ibn Qudaamah (may Allaah have mercy on him) narrated that
al-Qaadi Abu Ya’la said, speaking of an oath to divorce and differentiating
between that and a statement of divorce that is intended as such: This is
his stipulating a condition by means of which he intends to encourage her to
do something, or prevent her from doing something, such as saying, “If you
enter the house then you are divorced”, or “if you do not enter the house
then you are divorced.” 

With regard to a statement of divorce other than that, such
as saying, “You are divorced when the sun rises”, or “when the pilgrim comes
back”, or “if the ruler does not come,” this is a statement of divorce which
is intended as such and is not an oath.  

End quote from al-Mughni, 7/333 

Shaykh Ibn Baaz (may
Allaah have mercy on him) said: An oath to divorce is a statement of divorce
by means of which the person intends to encourage (his wife) to do
something, or to prevent her from doing something, or to urge his listeners
to believe him or disbelieve him. This is the oath to divorce which is
intended to encourage or discourage something, or to confirm or deny
something, unlike a statement of divorce which is intended as such, which
cannot be regarded as an oath, such as saying, “When the sun rises, my wife
is divorced,” or “When Ramadaan comes, my wife is divorced.” This is not
described as an oath (yameen), rather it is simply a statement of divorce in
which a condition is stipulated, and when the stipulated event takes place,
the divorce comes into effect. If he says for example, “When Ramadaan comes
my wife is divorced,” then the divorce takes effect when Ramadaan begins. If
he says, “When the sun rises, my wife is divorced,” then the divorce takes
effect when the sun rises. 

And he said: But if there is no encouragement or
discouragement, rather it is simply stipulating a condition, then this is a
statement of divorce in which the divorce counts as such, as stated above,
such as if he says: “When the month of Ramadaan begins then my wife is
divorced.” This is stipulating a condition, and when that happens the
divorce takes effect, because the thing that is attached to a condition
takes effect when the condition comes to pass. This is the basic principle.”
End quote from Fataawa al-Talaaq, p. 129-131 

The Standing Committee
was asked about a man who said to his wife: When your period comes then you
are purified, then you are divorced, but after that he decided to keep his
wife and not divorce her. 

They replied: This is a
divorce that is connected to a stipulated condition, and he did not intend
thereby to encourage her to do something or prevent her from doing
something, so the divorce takes effect when that condition comes to pass,
which is her purification after her menses. Recanting this condition after
it has come to pass is not valid. End quote.

Fataawa la-Lajnah al-Daa’imah,
20/174 

And Allaah knows best.