Need to find title of this film

I am trying to find the title of this film I watched a film in the 1980s about an American who was living in a communist controlled South East Asian country.

 

The Soviet officer was attached to the local garrison and set a local girl to spy on him.

 

Not only did the girl fell for the American (of course), the Russian also lost to the Americans in a boxing match.

 

Finally, the American was expelled, but vowed to come back for the girl, who held off the advances of the Russian by demanding proper status, despite the Russian already having a wife back in Moscow.

 

The American got a couple of friends to train him in scuba diving, the plan was to return and escape with the girl by swimming along the riverbed to the other side (home free).

 

Some of the scenes I recalled:

 

1. Opening - the American bloke was training for his scuba run, and recalled the previous events through flashbacks.

 

2. The American and the locals (Vietnamese?) being caught by the garrison on an illegal ferry. The Russian was leading the soldiers and told the American "From now on, stay home." after inspecting his passport.

 

3. The American going around the village, taking photo of the girl who was doing a native dance.

 

4. Boxing match between the Russian and the American, watched by a crowd of local soldiers rooting for the former.

 

5. The Russian storming at the girl "I told you to watch him, not sleep with him."

 

6. The girl telling the Russian "I am not a prostitute." - proper status require her to be installed as a mistress in her own house.

 

7. The Russian talking to the girl's father, waiting to fetch her.

Father : "Can she come back and visit us?"

Russian : "Of course, families should be closed together."

...

Father : "She should be back soon. She took her little sister fishing in the river."

Russian : "What??!!!!!"