21.   The rugged frontier has been a source of tension, with separatist rebels crossing the ill-defined border to escape clashes with Indonesian troops.

22.   The Russian troops clash frequently along with rugged frontier with Tajik rebels based in Afghanistan.

23.   The war formally ended this summer, but drug smuggling from Afghanistan remains a serious problem along the rugged frontier.

24.   The war formally ended with a peace deal in June, but drug smugglers remain active along the rugged frontier.

25.   To the west, Pakistani forces patrol the rugged Afghan frontier, guarding mountain passes to help the United States stop al-Qaida fugitives from creeping in.

26.   When night settles on the gaudy cinema district of this rugged frontier city, teenage boys prowl the narrow streets looking for customers.

27.   India demanded an end to the infiltration of such fighters across the rugged Himalayan frontier before withdrawing its troops.

28.   Indian defence sources said Indian and Pakistani troops exchanged heavy machine gun fire from midnight to dawn on Sunday at seven places along the rugged frontier.

29.   Indian defence sources said troops were exchanging heavy machine gun fire Sunday at seven places along the rugged frontier that divides Indian- and Pakistani-held Kashmir.

30.   The rugged northeastern frontier region is home to several guerrilla groups opposed to Indian rule which have frequently targeted army and paramilitary troops with landmines and bombs.